David Letterman paid a lengthy tribute to Robin Williams on his talk show last night (18.08.14).
The 'Late Show' host - making his first appearance since the actor's suicide last Monday (11.08.14) - showed a collection of moments from the 'Hook' star's "almost 50" appearances on the programme and apologised for the fact he had "no idea" how depressed his friend had been.
He said: "What I will add here is beyond being a very talented man, and a good friend and a gentleman, I'm sorry, like everybody else, I had no idea that the man was in pain, that the man was suffering. But what a guy, Robin Williams."
The 67-year-old presenter recalled how he and Robin had met at The Comedy Store in Los Angeles over 38 years ago and he had been ready to "make fun of the new guy" - but was left fearing for his career as the newcomer was so good.
He said: " "All of a sudden he comes up on the stage and - you know what it is - it's like nothing we had ever seen before, nothing we had ever imagined before.
"And then he finishes and I thought, ''Oh that's it, they're gonna have to put an end to showbusiness because what could happen after this?' Honest to God you thought, 'Holy crap, there goes my chance in showbusiness.' "
David then spoke of how he got his break as his friend invited him
to be a guest on his sitcom 'Mork and Mindy', and went on to recall how he was always "so gracious" as a talk show guest.
He said: "And we would talk about the old times and never did he act like, ''Oh I knew you guys were so scared because I was so good'. It was just a pleasure to know the guy."

Daniel Radcliffe never wants to be "separated" from Harry Potter.
The 25-year-old actor shot to fame aged 11 playing the boy wizard in the hit film series and though he has taken on a number of different roles since, he knows he will always be associated with his breakthrough part.
Speaking at a Q and A for his new film 'What If' at a London Apple Store, he said: "I don't think there's ever going to be one film in people's minds that finally separates me from Harry and I don't think I ever will be separated from Harry and I don't want to be.
"It was an incredibly important part of my life and something I still love and I'm very proud of, but I think this film, like 'Kill Your Darlings' was and like 'The Woman in Black' was, is just another step in showing people that I am interested in doing other things and that I'm just going to be sort of popping up as an actor now, doing jobs away from the world you might have seen me in in the past."
Daniel also admitted he enjoyed working on his new movie because it was so much lighter than his recent material.
He explained: "I'd never done comedy really on screen before, he explained. 'To be able to do a whole film where your job every day was to turn up and make the person in the scene with you laugh rather than to have some sort of emotional breakdown or save a dying child from a train, or whatever it is I've done in other films.
"It was nice to be able to turn up and be myself every day. I mean, it is the most like myself of any character I've ever played I think."
The 'Horns' star naturally gravitiates towards "very dark" material.
He added: "I've made a lot of very dark films since Potter and it's not necessarily that that's a choice it's just that's the kind of stuff I gravitate towards so it was nice to find something that was light and you felt would make people happy."

Julianne Hough is set to return to 'Dancing with the Stars' as a judge. The two-time dancing champion of the ABC show quit the programme after 2009's eighth series to pursue a music and film career, but she is reportedly in line to take up a new role...

Iggy Azalea has been blasted for her moody behaviour on the set of her new TV show.
The 'Fancy' hitmaker is the new host of MTV's 'House of Style' and reportedly spent much of filming at the Versace store in Beverly Hills on August 9 with a "complete scowl" on her face.
A source told the Hollywood Reporter: "Iggy walked in with her entourage and wouldn't take her sunglasses off the whole time we were in the store shooting her.
"She had a complete scowl the whole time and never cracked a smile -- unless the cameras were on. And the minute they stopped, it was back to scowling."
According to the source, even when the shoot moved outside the store to where fans had gathered, the 24-year-old rapper still refused to smile.
In contract, Iggy's guest for the episode, 'American Idol' judge Jennifer Lopez, was a delight to work with.
The production crew member revealed: "J.Lo was all smiles, saying hello to everyone on the crew, shaking everyone's hand and doing everything we needed her to do."
A spokesperson for the Australian star hasn't commented on the claims.

Peter Capaldi is trying to bring "mystery and strangeness" back to 'Doctor Who'.
The 56-year-old actor is to take on the role of the titular Time Lord for the first time in the upcoming latest instalment of the BBC One sci-fi programme and he's confessed that although he's almost finished filming his first series, he's still finding his feet as the character.
He explained: "I don't know if it's quite fallen into place yet. I think it's a mistake to get it to click, to get it to groove. I've tried to avoid finding a way to it and then just repeating that.
"I'm trying all the time to see what works and what doesn't work, though I'm trying to bring back some of the Doctor's mystery and strangeness, which is hard to do given that the show is 50 years old."
Capaldi has previously admitted that he's been a fan of 'Doctor Who' since he was five-years-old and confessed he already knew how to use the Tardis before he started filming, but he's now revealed he never dreamed he'd be offered the role of the Doctor himself.
Speaking to the Radio Times magazine, he said: "I think I'm a more grown-up Doctor. He is serious when he needs to be, but still quite comic.
"Then I never thought I'd be in the frame for the part as the Doctors were getting younger and younger."
Peter makes his debut as the Time Lord on BBC One on Saturday (23.08.14).

Vicky Pattison's mum wouldn't speak to her after her on-screen romp.
The 'Geordie Shore' star has revealed that her family were mortified when she first slept with her now ex-fiance Ricci Guarnaccio on the second series of the MTV show.
Vicky said: "The worst thing about having sex on TV was that my mam stopped speaking to me for ages when she found out.
"Yes, sometimes my language is appalling. I can be violent but those things mam can overlook. But having sex on TV is very different."
The 27-year-old beauty - who recently returned to the reality show house in Newcastle with co-stars including Gary 'Gaz' Beadle, Charlotte Crosby and Holly Hagan - also confessed she felt as though she'd lost the respect of her fans when she shared the intimate moment on-screen.
In an extract from her new autobiography 'Nothing But The Truth' printed in The Sun newspaper, she explains: "I think that scene really changed the public's opinion of me and it also changed my opinion of the show because it took everything from me."
Vicky added: "I hated having sex on camera so much. The bitching is nasty but I'm actually a bit of a prude when it comes to that side of things. I despised that my parents could potentially see it."
The feisty brunette is now dating ice hockey player James Morgan and she's vowed to keep their relationship out of the public eye.

Denise Van Outen doesn't want any more children.
The former 'Big Breakfast' host has revealed that although she's currently loved up with stockbroker Eddie Boxshall - who is her first boyfriend since her split from husband Lee Mead - she's not interested in making any siblings for her four-year-old daughter Betsy.
Quizzed on whether she wanted any more children, she said: "I don't think so. No. I've been very blessed with my little girl. She has grown up so fast. They grow up really quickly - she starts school in September. I can't believe it. I'm excited about her starting school."
The blonde beauty celebrated her 40th birthday in May and she's confessed that although she still feels young at heart, she's not worried about getting older.
She told the Daily Mirror newspaper: "I feel all right about being 40. I had a really nice party with my girlfriends.
"I do feel 20 inside. I think you always feel young inside.
"My nan was in her 80s and she still felt 19."
Meanwhile, Denise previously admitted she had put her love life on hold out of respect for Lee, whom she was married to for four years before they split in July last year.
She said recently: "I've just got back on the dating scene after a year of healing and being respectful to my ex-partner and thinking, 'I want to do it the right way'."

Lee Ryan was kicked out of a hotel bar after he stripped down to his pants.
Lee, 31, spent his night off on tour drinking beer and vodka at the Crowne Plaza hotel in Glasgow, where he was chucked out at around 1am after stripping to his pants and dancing on the bar.
A witness told The Sun newspaper: "He was being egged on so started taking his clothes off. Next thing he jumped on the bar in only his pants and started dancing.
"A row broke out with staff telling Lee to get off and put some clothes on. He was then asked to leave the bar and went red-faced to his room."
Boyband Blue are currently appearing on 'Ant & Dec's Takeaway On Tour', which has seen them travel around the UK with their live show.
A spokesperson for Blue was keen to downplay the incident, saying: "Lee apologises for any upset and inconvenience caused."
Lee recently admitted to drinking heavily and suffering from depression in the aftermath of his appearance on 'Celebrity Big Brother' earlier this year.
The singer became unpopular with some of the public after finding himself in a love triangle with glamour model Casey Batchelor and American actress Jasmine Waltz.

Labrinth says Simon Cowell told him to take a break between albums.
The rapper has returned two years since the release of his debut album 'Electronic Earth', and he insisted part of the reason behind the long wait for new single 'Let It Be' was the advice of the media mogul.
He told The Sun newspaper: "I was like, 's**t, I don't have any follow-ups!'
"Then I saw Simon in St Tropez and he said, 'I just want you to have fun and do what you love. Even if it takes three years, make an amazing album.' "
The 'Beneath Your Beautiful' hitmaker is signed to the 'X Factor' boss' Syco Records label, and he was pushed to the limit when he did start working on the follow-up to his 2012 debut.
He revealed the effort he has been putting in for the record, which is said to combine 70s soul music and space-age sound effects.
He added: "I was in the studio three days with no sleep!"
Meanwhile, Rockboi recently ruled out a sibling rivalry with the 'Earthquake' star and 'Britain's Got Talent' drummer MckNasty.
He previously told BANG Showbiz: "Not unless we're having a pillow fight or something like that, you know what I mean.
"We've all worked together since we were really young and stuff so one day you never know, you might see the whole Mac' pack getting poppin' together."

Union J's JJ Hamblett says they are "good for the future of pop" music.
The 'Carry You' singer has insisted the group - who appeared on 'The X Factor' in 2012 - are much more than a typical boyband, and suggested they will stand out over time as something different.
He told the Daily Star newspaper: "You can call us a boyband but we have a lot more about us and that's gotta be good for the future of pop.
"[Jaymi Hensley] came out as gay very early on and I've become a dad recently."
Meanwhile, the group have been in the US working on their new album - the follow-up to last year's self-titled debut - and they have already noticed their popularity rising in Los Angeles.
JJ added: "We've been walking through Hollywood and people have asked for autographs - it's been nuts."
For Jaymi though, their fame an be difficult as he tries to plan a big wedding with partner Olly.
He explained: "Mags offered us all sorts to have our pictures taken and then we realised it shouldn't be about that."

Foxes and Rudimental have joined the line-up for iTunes Festival next month.
The 'Holding on to Heaven' hitmaker and 'Waiting All Night' stars are two of the latest acts to be confirmed for the month-long event at the Roundhouse in London, and they are excited to perform.
Foxes - who will support The Script on September 15 - said: "I'm honoured to be performing at the iTunes Festival this year alongside so many amazing acts. See you at The Roundhouse!"
Meanwhile, Rudimental are thrilled to be making their return to the annual event as headliners on September 20, having performed in 2012 alongside Ed Sheeran.
They added: "We're really excited to be playing the iTunes Festival again.
"A couple of years ago we played it for the first time supporting Ed Sheeran and had a lot of fun, so we can't wait to be back in the Roundhouse headlining!"
Other new headliners include Elbow, Paolo Nutini and David Gray, with a number of artists now confirmed for the festival.
The event opens on September 2 with Beck and Jenny Lewis, and will feature performances from the likes of Blondie, Pharrell Williams and 5 Seconds of Summer.

iTunes Festival Line-up:

September 2 - Beck + Jenny Lewis
September 3 - David Guetta + Clean Bandit + Robin Schulz
September 4 - 5 Seconds of Summer + Charlie Simpson
September 5 - Kasabian
September 7 - Calvin Harris + Kiesza
September 8 - Robert Plant + Luke Sital-Singh
September 9 - Sam Smith + SOHN
September 10 - Pharrell Williams + Jungle
September 11 - Maroon 5 + Matthew Koma
September 12 - Elbow
September 13 - Paolo Nutini
September 14 - David Gray
September 15 - The Script + Foxes
September 16 - Blondie + Chrissie Hynde
September 17 - Gregory Porter + Eric Whitacre
September 18 - Jessie Ware
September 20 - Rudimental + Jess Glynne
September 21 - Ryan Adams + First Aid Kit
September 26 - Lenny Kravitz
September 27 - Kylie + MNEK

The script for 'Star Trek 3' is nearing completion.
Roberto Orci, who is writing the script for the new flick alongside John D. Payne and Patrick McKay, confirmed an initial draft of the script has been completed and is set to be sent to bosses at Paramount, the studio behind the franchise.
The 41-year-old recently expressed an interest in directing the film, telling Collider: "I don't want to count my chickens before they hatch. The studio has yet to even read the script. I'm in the middle of writing it, with the talented team of [John D.] Payne and [Patrick] McKay.
"They are true Star Trek fans, as well. So, I can't even think anything about the future until I give them a script and they greenlight it. Until that happens, everything else is just a rumour."
Orci thinks he is a unique position to assume the role, saying: "Having seen one of the best guys in the business [J.J. Abrams] direct two of them already, and to have seen it from the vantage point of a producer too, I know where a lot of the challenges are and where a lot of the fun is."
'Star Trek 3' is expected to hit cinema screens in 2016.