Born in Nork, Surrey on 20 August 1971 to Peter, a London Transport engineer, and Kathleen Williams, a lab technician, Williams was brought up in Banstead. Both his parents appeared on The Friday Night Project when their son was the guest star on the show.

Williams was educated at Collingwood Primary School and the independent Reigate Grammar School (at the latter he was a contemporary of Robert Shearman). He was a member of the National Youth Theatre, which is where he met Matt Lucas. Williams studied drama at the University of Bristol, where he was in the 1989-92 cohort, one year below Simon Pegg.

Williams changed his name to Walliams () when he joined the actors' trade union, Equity, as there was already a member named David Williams. This was spoofed in a mock interview on Rock Profile, when Robbie Williams was continuously referred to as 'Robbie Walliams'.

His first known TV appearance was as "Lesley Luncheonmeat" on Sky1's show Games World in 1993. He appeared alongside Alex Verrey, who played Big Boy Barry, every Tuesday evening. After that he went on to be "The Lift" on the first series of the CBBC gameshow Incredible Games in 1994. He appeared together with The League of Gentlemen's Mark Gatiss, who wrote and appeared in Doctor Who parodies The Pitch of Fear, The Web of Caves and The Kidnappers for BBC2's "Doctor Who Night" in 1999. He later performed in the Big Finish Productions Doctor Who audio play Phantasmagoria, written by Gatiss.Walliams appeared along with Matt Lucas in the video of the Fat Les song Vindaloo (the unofficial anthem for the England national football team at the 1998 FIFA World Cup) and had a cameo role in a 1999 episode of Simon Pegg's Spaced (1x3 "Art") as Vulva, an artist/collaborator from Brian's past and now a self-proclaimed artist of impressionism.

In 2000, he played Jake Plaskow in the BBC's Attachments, set in an internet start-up company. In 2001 he was one of the leads in Cruise of the Gods. He also appeared in EastEnders in 2003, and the second episode of Marple.

From 2003 to 2005 Walliam co-wrote and co-starred in three series of the popular BBC TV character sketch show Little Britain with Matt Lucas, first airing on BBC3 before moving across to the main BBC1 channel. A successful live stage show of the series, Little Britain Live was produced in 2006. A number of seasonal and charity specials followed, up to 2009. A spin-off series produced in the USA by HBO, Little Britain USA, followed in 2008, a second series of which is due to air in 2010.

In 2005 Walliams starred in the video for Charlotte Hatherley single Bastardo along with Simon Pegg, Lucy Davis and Lauren Laverne. In 2006, Walliams made an appearance in the film A Cock and Bull Story. Later in the year he presented a documentary on James Bond, entitled David Walliams: My Life with James Bond. In 2007 he returned to non-comedic television, garnering excellent reviews for his portrayal of a suave and dangerous manipulator in Stephen Poliakoff's Capturing Mary as well as appearing in the film Virgin Territory. In September 2007, Walliams appeared in the comedy film, Run, Fat Boy, Run. Walliams portrayed comedian Frankie Howerd in the BBC4 TV film Rather You Than Me. On 26 August 2008, he made his stage debut at the internationally renowned Gate Theatre in Dublin, opposite Michael Gambon in Harold Pinter's No Man's Land, in front of an audience that included Pinter himself. The production transferred to London later in the year. In 2010, Walliams appeared alongside Paul Rudd and Steve Carell in the comedy Dinner for Schmucks.

Walliams has also appeared in Series 7, Episode 6 of the BBC-2 and BBC America show Top Gear.

Walliams and Lucas

Walliams and Matt Lucas both worked on Vic and Bob's series, Bang Bang, It's Reeves and Mortimer, in the late 1990s, playing minor roles in sketches such as The Club. Walliams and Lucas played grotesque caricatures of various rock musicians in the series Rock Profile and in the spoof documentary series Sir Bernard's Stately Homes. They were also stars of the Paramount Comedy Channel show Mash and Peas, and it was in this guise that they appeared in the Fat Les video (see above). They also had small roles in Plunkett and Maclaine as prisoners.

They have appeared together in a music video for the Pet Shop Boys single "I'm with Stupid", in which the two are apparently auditioning their version of the song's video for Neil Tennant and Chris Lowe, who are tied up and appear to be hostages.

The pair are most famous for Little Britain which ran from 2003-2009 on BBC in the UK and from 2008 onwards in HBO in the USA. Little Britain is a character-driven sketch show in which recurring characters appear in a variety of situations exhibiting particular catchphrases or idiosyncratic behaviours. Among the characters Walliams played were Emily Howard, a deluded "transvestite", Ray McCooney, an insane Scottish hotel owner, and Sebastian Love, an aide de camp to the Prime Minister, on whom Love has a huge crush.

The characters from Little Britain played by Walliams and Lucas appeared in a 2010 UK television advertising campaign for the Nationwide Building Society.

They are working on a new series called "Come Fly With Me", a six-part series that is scheduled to start broadcasting in the second half of 2010.

The English Channel

In 2006, as Walliams and Lucas toured Britain with a stage show, Little Britain Live, Walliams managed to fit in two hours of swimming training every morning in preparation for his cross-channel swim. On 3 April 2005, the swimming pool scene featuring Lou & Andy was hailed as the greatest comedy sketch of all time in a Channel 4 poll, on the show The 50 Greatest Comedy Sketches.

Walliams took up swimming as a youth as his preferred form of exercise, because he was overweight. On 4 July 2006 he swam the English Channel for the charity Sport Relief (part of Comic Relief). He completed the swim in 10 hours and 34 minutes to cover the 35 km (22 miles) stretch of sea, the equivalent of 700 lengths of an Olympic standard swimming pool. This was wrongly reported as one of the top 50 recorded times for an unaided Channel crossing: in reality Walliams actually placed 167th at the time of crossing in only the CSA listings, excluding the CSPF listings. He did raise over £1,000,000 in donations. Under the supervision of his trainer, he trained for nine months to prepare for the swim. The training had to coincide with Walliams and Lucas's Little Britain Live tour, so every day he had to complete several hours of training before performing on stage in the evening. Walliams first swam from Lee-on-the-Solent near Portsmouth, Hampshire to the Isle Of Wight in around 2 hours and he also completed an eight hour swim off the coast of Croatia before embarking on the cross-channel attempt. Walliams has insisted that prior to his challenge he had never seriously taken part in any sport. The Bluetones' lead singer Mark Morriss wrote a song, "Fade In/Fade Out", in honour of Walliams' achievement; the song can be found on their self-titled album, which was released on 9 October 2006.

The Strait of Gibraltar

On 7 March 2008, Walliams along with James Cracknell swam the 12 miles (19 km) Strait of Gibraltar, from Spain to Morocco, again for Sport Relief. He successfully completed the swim in just over 4 and a half hours.

In March 2010 Walliams and a group of celebrities cycled an end to end journey through the UK, raising over one million British pounds for Sport Relief. Walliams suffered a serious fall when tackling Kirkstone Pass, a thousand feet climb in the Lake District, but was able to complete the ride.

In early 2008 Walliams signed a contract with HarperCollins to publish two children's books. The debut novel, The Boy In The Dress, illustrated by Quentin Blake, was released worldwide on 1 November 2008. It explores several of the themes of Little Britain from Walliams' own life on a more emotional level, such as the "camp" humour of cross-dressing and effeminacy. The story recounts a neglected 12-year-old boy's search for a female role model, his friendship with the popular girl in school, and the ways in which relationships develop along gender lines.

In November 2009 came Mr Stink, illustrated by Quentin Blake, about a small 12-year-old girl called Chloe, who meets a tramp and helps to look after him. She keeps him hidden from her family. The book consists of 26 illustrated chapters full of jokes. It is aimed at teenagers and children over 9. The book was awarded the Children's Award in the inaugural People's Book Prize in 2010.

Walliams was awarded a special award in the BBC Sports Personality of the Year in recognition. Matt Lucas made a documentary of this, entitled Little Britain's Big Swim, which can be found on the Little Britain Live DVD. On 6 November 2006, he won The Mirror's "Pride of Britain" Award for the Most Influential Public Figure as he raised more than £1 million swimming the channel for the charity Sport Relief. Although initially tipped as a contender for the BBC's Sports Personality of the Year poll for 2006, he failed to make the final shortlist of 10 contenders. Walliams was given a special award during the ceremony for his achievement. In July 2006, Walliams became Patron of Cardiac Risk in the Young (CRY), a charity.

In 2009, Walliams began dating Dutch model Lara Stone. On 20 January 2010, it became known that they were engaged. Walliams proposed to Stone in Los Angeles, after her parents gave their blessing to the relationship. He has previously been romantically linked to Patsy Kensit, Abi Titmuss, Emily Scott and model Lauren Budd. On 16 May 2010, the couple married at central London's Claridge's hotel.

Mr Walliams has been known to suffer from depression, and has described his 2006 swim of the English Channel as "some sort of redemption".