Joss Whedon says Ultron is "everything a robot never is".
The 49-year-old director is working on 'Avengers: Age of Ultron' and he's been having a "blast" developing the character which is played by James Spader.
He explained to Empire magazine: "I'm having a blast with Ultron.
"He's not a creature of logic - he's a robot who's genuinely disturbed. We're finding out what makes him menacing and at the same time endearing and funny and strange and unexpected, and everything a robot never is."
Spader joins an A-List cast including Robert Downey (Iron Man),
Chris Hemsworth (Thor), Mark Ruffalo (The Hulk), Chris Evans (Captain America), Scarlett Johansson (Black Widow), and Samuel L. Jackson (Nick Fury).
Although there a number of big names Whedon insists every character in the forthcoming epic has a significant role to play.
He explained: "I fiercely dislike the idea of just throwing in more people for the sake of doing that.
"But last time I had all of Earth's Mightiest Heroes versus one British character actor, and I needed more conflict."
The filmmaker wants to bring a different aesthetic to the picture to make sure it isn't too similar to 2002's 'The Avengers'.
He added: "The number of different looks and textures and moods we're getting from the British locations is stupid awesome, because this, palette-wise, is very different. I'm trying to make a different film. Because why would you make one movie twice? That seems weird."

Ciara has been wearing her fiancé's clothes throughout her pregnancy.
The 'Goodies' singer is due to give birth to her first child any when now, and she admits her beau Future's wardrobe has been her saviour over the last nine months.
She explained: "I feel like pregnancy has been a great fashion challenge because you can't wear things that you used to wear and you still want to feel like who you are. I have to pay some credit to my fiancé's closet, because I literally have worn probably all of his clothes."
However, the 28-year-old star admits it's been nice to relax her gym routine and embrace her changing figure.
Speaking to WMag.com, she said: "It feels good to not have to wonder whether your abs are tight enough. I like not being so perfect."
Meanwhile, the couple - who got engaged in October last year - announced they are expecting their first child together in January.
The brunette beauty has remained tight-lipped on the sex of the tot, but Future let slip that their firstborn was likely to be a boy after referring to the baby as "him" in an interview.
Ciara has been busy preparing for the arrival of her child and invited a dozen of her closest pals, including Kim Kardashian and Kris Jenner, to her baby shower in West Hollywood, California, last month.
Kim reportedly confirmed rumours the couple were expecting a baby boy after she bought them a giant basket containing a blue car toy and a pirate's hat.

Nicole Richie and Joel Madden are selling their Spanish-style home for $1.87 million. The couple, who bought the house in November 2008 for $1.8 million, put the luxurious property in Glendale, Los Angeles, on the market on Monday (21.04.14). The ho...

Tamera Mowry didn't want to rush to lose her baby weight.
The 35-year-old actress, who now weighs 127lbs, didn't want to follow in the footsteps of other celebrity mothers by springing back into shape straight after giving birth because she wanted to spend time with her son.
She quipped: "I want to punch them [other celebrities who lose weight quickly] in the face."
She added to InTouch magazine: "I wanted to spend time bonding with my baby, not killing myself at the gym."
The brunette beauty - who has 17-month-old son Aden with her husband Adam Housley - stripped down to her bikini for the magazine and revealed it was the first time she's been in a two-piece since her honeymoon in 2011.
She explained: "It's the first time I've been in a bikini since my honeymoon. I feel great."
Tamera's pregnancy news came as a shock to fans as she and Adam had claimed they were not interested in starting a family together any time soon.
However, after a trip to South Africa shortly after their wedding, they changed their minds.
She said at the time: "It's just so beautiful there and you get a whole new perspective on life, the things that really matter. Adam and I looked at each other and said, 'Why wait?'"

Bethenny Frankel has been ordered to pay $100,000 to her ex-husband Jason Hoppy's attorney.
The TV personality has been forced to cover her former lover's legal fees as their divorce enters its 16th month, but it is believe she will be reimbursed once they have reached a settlement, according to TMZ.com.
According to court documents obtained by the site, the brunette beauty "has to immediately hand over what amounts to an advance payment to Jason's attorney."
Since filing for divorce in December 2012, the former couple have been locked in a bitter legal battle over the custody of their three-year-old daughter Bryn and the money that was made during their two-year marriage.
However, a source told RadarOnline.com: "Jason would like to get the divorce and custody settled, once and for all but Bethenny is making it impossible."
Meanwhile, it was recently reported that Bryn has been ordered to undergo a psychiatric evaluation as part of the proceedings and the ex-lovers must hand over all past mental and health records for their daughter.
Bethenny and Jason initially filed for joint custody, but as time went on and tensions grew, the former 'Real Housewife of New York' star changed her mind and is now going for full custody with Jason being allowed visitation.

Liam Gallagher has sparked rumours Oasis are going to reform with a series of cryptic Twitter posts.
The former frontman has hinted at a reunion after taking to the social networking site tonight (24.04.14) to individually tweet the letters of the band's name every half hour.
The 41-year-old musician was inundated with messages from his fans asking him what his posts meant after he posted the final letter, 'S', on his account.
One fan, Chloe Dylan, wrote: "liamgallagher what does this mean? (sic)."
Another, franz fennynand, added: "Liam GallaGHER WHAT R U TRYING TO TELL US. (sic)".
Meanwhile, others were over the moon after assuming the band had already got back together.
Jonathan James tweeted: "Oasis are BACK its official liamgallagher said so !!!! Brilliant news. (sic)".
Liam failed to elaborate on his tweets, but simple followed up with: "OASIS LG (sic)".
The mysterious posts come just two months after Oasis announced they are re-releasing their debut album 'Definitely Maybe' with previously unheard tracks to celebrate the LP's 20th anniversary on May 19.
The band split in August 2009 after Liam and his brother Noel had a huge backstage bust-up in Paris, France, but rumours are beginning to circulate that they could be planning to headline at Glastonbury this year.
However, Noel turned down £20million to reunite with the Beady Eye frontman for an Oasis world tour in December last year.

Fergie's baby son has started talking.
The Black Eyed Peas frontwoman has revealed seven-month-old Axl Jack - her first child with husband Josh Duhamel - is beginning to experiment with words.
Fergie explained to E! News: " He's actually talking now--well, formulating what he thinks are words. We're just kind of trying to figure it out. He keeps saying, 'Ba, ba', we think it's ball. He says it when the ball's around so we're thinking first word, ball - maybe?
"He also says, 'Ma ma ma'. I don't know if he's directing it towards me, but I'm thinking mama."
The 39-year-old singer recently admitted she and Josh, who got married in January 2009, have been trying to teach the cute tot little easy words.
She said last month: "The best part of being a mum is just hanging out with my kid. He's my homie! I'm just listening, talking back with him and trying to teach him words like 'nose' and 'dancing'. Daddy is trying to teach him 'ball' and I'm trying to teach him 'dance'."
Axl has also been using "high-pitched" squeals to get his parents attention and express when he's excited.
Fergie explained: "He's a screamer! There's always this high-pitched scream going throughout the house. It's not him complaining or crying. He just gets excited and he wants to scream!"

Miley Cyrus has been discharged from hospital.
The 'Wrecking Ball' hitmaker is "feeling much better" after spending over a week under the watchful eye of doctors following a severe allergic reaction to antibiotics.
A source told E! News: "She is feeling much better and Europe [tour] is still on."
The 21-year-old singer, who was hospitalised on April 15, was forced to reschedule her US 'Bangerz' tour after her body rejected Cephalexin she was taking to treat a sinus infection, but the European leg of the tour, which is scheduled to kick off on May 2, will proceed as planned.
A statement released on her website last week said: "All remaining US dates on the Miley Cyrus 'Bangerz' tour have been postponed. Miley is continuing to recover from the severe allergic reaction she suffered on April 15.
"Existing tickets will be honoured on the new dates, which include previously cancelled and postponed dates."
The blonde beauty vented her frustration from her hospital bed last week after she was forced to cancel her show in her hometown Nashville, Tennessee, on April 17.
She wrote on Twitter at the time: "Sick of waking up to needles #goingthruit #floydfriday (sic)."
Miley's illness follows her devastation after her beloved dog Floyd passed away earlier this month, which left her feeling "exhausted" and "physically sick".

Olivia Wilde's newborn son has peed on his own face.
The 'Drinking Buddies' star took to Twitter today (24.04.14) to announce that her one-day-old son Otis Alexander, whom she shares with her fiancé Jason Sudeikis, has urinated on himself already.
She wrote: "Having an infant son alerts me to the fact that every man, at one point, has peed on his own face. #awesome (sic)".
The 30-year-old beauty announced the birth of Otis, who was due on May 4, on Twitter yesterday (23.04.14) after welcoming him into the world two weeks early.
She tweeted: "Ladies and gentlemen, Otis Alexander Sudeikis has LEFT the building! (I'm the building). (sic)".
She also shared a black and white image of herself cuddling the newborn in a blanket.
The brunette beauty, who got engaged to Jason in January 2013, recently gushed about the bond she had formed with her son while pregnant.
She said: "He's moving around in there and no one else can tell - it's a little secret friendship."
The 'Rush' star also spoke about embracing her changing body during her pregnancy.
She said: "I just thought, Oh I'm going to hide this forever. But I ended up getting kind of excited to show the bump, as a badge of pride. Like, I'm a woman! Look at me making a human! I am a goddess!"
Olivia was previously married to Italian prince Tao Ruspoli for eight years until 2011.

Aaron Carter wants to "sweep" Hilary Duff "off her feet".
The former pop star dated the 26-year-old singer-and-actress for 18 months when they were teenagers, but he now wants the chance to rekindle their romance.
Speaking to 'Entertainment Tonight', he said: "I don't know who she is today, she doesn't know who I am today, but I would sweep her off her feet if I ever got a chance to again and fix what I did wrong."
The former couple, who dated for three years, ended their on-again/off-again relationship in 2003 after Aaron cheated on the blonde beauty with Lindsay Lohan.
Aaron has previously spoken of his regret at cheating on Hilary with her then-best friend.
He has said in the past: "I started dating Hilary on my 13th birthday... I was dating her for like a year-and-a-half and then I just got a little bored so I went and I started getting to know Lindsay, dating Lindsay.
"Then I didn't want to do that anymore, so I got back with Hilary. And then I ended up cheating on Hilary with her best friend. That's nothing to smile about. She wasn't even that good looking either."
Earlier this year, Aaron declared his love for Hilary - who announced she had separated from husband Mike Comrie after three years of marriage in January - in a number of cryptic posts on Twitter.
He said: "Don't be that stupid douche that loses the love of your life forever.. Like me..
"I'll spend the rest of my life trying to better myself to get back to her. (sic)."

Carmen Electra has split from Tal Cooperman.
The 41-year-old actress and the 30-year-old clothing mogul have called time on their brief relationship after deciding to go their separate ways.
A source told E! News: "They split almost two weeks ago. They weren't really dating per se, just dates here and there. They hadn't been doing too well."
However, just last month, the former 'Baywatch' beauty claimed she was "really happy" with Tal after being introduced by mutual friends three months earlier.
Carmen, who had a brief relationship with Simon Cowell last year, said: "We are taking it slow and really trying to get to know each other, but so far we are really happy! He's gorgeous and a lot of fun."
Meanwhile, news of the split comes just hours after Carmen's ex-husband Dave Navarro shared a picture on Twitter of him touching tongues with the blonde beauty.
He accompanied the cheeky snap with the caption: "May get lucky with this one tonight!"
However, despite the endearing photograph, sources claim the former couple, who got married in 2003 before divorcing in 2006, are not rekindling their romance.
A source said: "They aren't rekindling anything. They've always been really good friends. Just friends who really get along well."
Carmen was also married to Dennis Rodman in 1998 before their romance ended in 1999.
She also got engaged to rocker Rob Patterson in 2009 before the pair split up in October 2012.

Kris Jenner's sister claims Bruce "walked out" on her.
The reality TV star's younger sibling Karen Houghton believes it was the Olympic gold medallist, not Kris, who called time on their 22-year marriage in October.
Karen told RadarOnline.com: "Bruce left. He walked out on her, and I think he's not coming back. He couldn't take the yelling anymore and stuff. I think she's got issues right now because Bruce left her."
Although, the 53-year-old nurse insists Kris and Bruce's separation has done them the world of good because now they're "not on each other's backs all the time and yelling at each other telling each other what to do."
However, the former couple - who have biological daughters Kendall, 18, and Kylie, 16, as well as eight other children from previous relationships - have recently sparked rumours of a reconciliation after they were spotted walking hand-in-hand in Los Angeles in March.
Bruce, 64, even drove from his bachelor pad in Malibu to Thousand Oaks, Los Angeles, last week to be by Kris' side after she was hospitalised for mysterious "internal pains".
Earlier this week, the 'Keeping Up With the Kardashians' star also declared her love for Bruce by posting a touching tribute online to celebrate their 23rd wedding anniversary.
The matriarch shared an old photograph of them on Instagram, with the caption: "Happy Anniversary to one of the most amazing men I know!!!! I love you, Wow 23 years!!!!! #love #weareofficiallyvintage (sic)."