British actor Kenny Baker, who starred as R2-D2 in six Star Wars films, has died aged 81 after a long illness, his niece has confirmed.
Baker made his name as the robot in the first Star Wars film in 1977 alongside Anthony Daniels's C-3PO character.
Star Wars creator George Lucas paid tribute to a "real gentleman" and Mark Hamill - Luke Skywalker in the films - said he had lost "a lifelong friend".
Born in Birmingham, Baker's other films include Time Bandits and Flash Gordon.
After starring in the original Star Wars film he went on to appear in the sequels, The Empire Strikes Back and Return of the Jedi, and the three prequels between 1999 and 2005.
He later appeared at Star Wars fan conventions across the world.
Baker's agent Johnny Mans said the actor had been ill for a couple of years.
He said: "Kenny was truly a great friend, one of the nicest guys you could ever wish to meet, and a fabulous and talented performer."
Mans described him as "a one-off" saying he would "never forget the laughs we shared over the years".
"He will be sadly missed," he added.
Lucas said: "Kenny Baker was a real gentleman as well as an incredible trooper who always worked hard under difficult circumstances.
"A talented vaudevillian who could always make everybody laugh, Kenny was truly the heart and soul of R2-D2 and will be missed by all his fans and everyone who knew him."
Baker's nephew, Drew Myerscough, said he had cared for Baker for "eight or nine years" after he developed respiratory problems.
He said his uncle, who lived in Preston, had a passion for wildlife documentaries and had "a liking for lasagne".
"He was just a normal, down-to-earth, regular guy that enjoyed life," he told the BBC.
He said the pair "rarely" discussed Star Wars, but added: "His fans worldwide kept him going and he loved nothing more than going to conventions and meeting everybody - it really gave him that extra lease of life."
The 3ft 8in (1.12m) actor began performing in 1950 at the age of 16, working as a circus clown and in pantomime.
Baker initially turned down the role of mischievous droid R2-D2, famous for his whistles and beeps. In an interview on his website he recalled telling George Lucas: "I don't want to be stuck in a robot, what for, for goodness' sake?
'Like a boiled egg'
He added: "I said, 'I'll help you out, I'll do you a favour.' George said, 'You've got to do it, we can't find anyone else. You're small, to get into it [the costume], and you're strong enough to be able to move in it,' - and they couldn't use kids.
"I could work all hours, so I was a godsend to them. They'd made the robot in rough form and I was the only one around at the time that was just right for it.
"I got into it and they put the lid on me like a boiled egg."
In another interview, Baker said Sir Alec Guinness's decision to appear in Star Wars convinced him to sign up.
"I thought if Alec Guinness is in it, he knows more than I do about filming, that's for sure. It must be a decent film otherwise he wouldn't be in it."
Writing on Twitter, Hamill said: "Goodbye #KennyBaker A lifelong loyal friend-I loved his optimism & determination He WAS the droid I was looking for!"
Ewan McGregor, who played Obi-Wan Kenobi in the three Star Wars prequels, tweeted: "So sorry to hear about this. It was lovely working with Kenny."
The studio behind the original Star Wars films, 20th Century Fox, posted a still of R2-D2 and C-3PO and said: "Rest in peace, Kenny Baker, the heart and soul of R2-D2."
Actor Daniel Logan, who played Boba Fett in 2002's Star Wars: Episode II - Attack of the Clones, tweeted: "So sad to hear one of my dearest friends passed away. Rest in peace Kenny Baker. Love you. Will miss you!"
In a statement on starwars.com, Lucasfilm president Kathleen Kennedy said: "There is no Star Wars without R2-D2, and Kenny defined who R2-D2 was and is."
Baker was a consultant on the last Star Wars production - The Force Awakens - but British actor Jimmy Vee was already lined up to take on the role of R2-D2 in the next film, due for release in 2017.
Despite the fame R2-D2 brought him, Baker told the BBC in 2001 that his own favourite screen role was as Fidgit in 1981's Time Bandits.
The comic fantasy about a boy who joins a group of time-travelling dwarves who hunt for treasure to steal starred Sean Connery and John Cleese.
"The director Terry Gilliam's such a nutcase, he's so enthusiastic, you can't help enjoy it. It was just a fun film to make," Baker said.
A father of two, Baker's wife Eileen died in 1993.
On his website, Baker also recalled working with comedians including Ken Dodd, Little and Large, Russ Abbot, Ben Elton, Dick Emery and Dave Allen and once meeting Laurel and Hardy.
He became part of a musical comedy act called The Mini Tones and later performed with his friend Jack Purvis in nightclubs.
Both men went on to appear in the original Star Wars film which was shot at Elstree studios in 1976, with Purvis playing the chief Jawa.
In 1978, as R2-D2, Baker put his footprints into concrete outside Graumann's Chinese Theatre in Hollywood.
Baker also appeared on screen in Mona Lisa, Amadeus, and The Elephant Man.