- Keith worked as a radio broadcaster, but left the job after only a few months when he felt that he had nothing left to say.
- In the late 70s, Keith cut an album with The Atoms called Max Bygraves Killed My Mother. All 2,000 copies sold out.
- In the past, Keith has also done stints in a borstal and prison.
- Keith has had a myriad of jobs over the years, all of which he claims to have enjoyed. Including the positions coal miner, printer, meat packer, engineer, window cleaner and a stagehand.
- It has been said, Keith was born at almost the precise moment Princess Elizabeth was crowned Queen of Great Britain and the Commonwealth.
- Keith has been married and divorced twice - first to producer Alison Owen, then to producer Nira Park. He has also been romantically involved with actress Julia Sawalha (of Ab Fab fame) and currently with former Bodies co-star Tamzin Malleson.
- In 1999, Keith appeared in a TV commercial for Listerine UK).
- Keith co-starred along with best mate Damien Hirst in Blur's music video Country House.
- Keith made an appearance in the Bjork video Play Dead.
- Keith, a devoted conservationist, is a supporter/patron of the Dorset Wildlife Trust.
- Keith co-wrote New Order's one and only number one song in the UK - World In Motion. He has also performed with them live.
- Keith is the older brother of actor/director Kevin Allen.
- Artist Damien Hurst is his best mate.
- Along with his fellow band members of Fat Les, Keith composed and performed the hit unofficial England Soccer World Cup 1998 song: "Vindaloo".
- KA supports Fulham Football Club.
- Keith stands 5' 6½" (1.69 m) tall.
- He once danced on stage with the Happy Mondays in New York City.
- Keith is a father of eight children, including singer Lily Allen, actor Alfie Owen-Allen and their sister Sarah Allen.
- Keith Allen: (on his daughter, singer Lily Allen) The one thing my daughter has got from me is the inability to shut up in interviews, and things just come out. Does Lily take after me in other ways? You judge [laughs]. Do print that we've never been estranged. In fact, we spent three of our most joyful years together going to see Fulham every Saturday. She used to get so excited, bless her.
- Keith Allen: I think Aleister Crowley said, 'Do what thou wilt shall be the whole of the Law.' That seems perfectly reasonable because it asks you to consider personal responsibility. People say, 'Well, what if you feel like murdering?' The answer is, don't feel like murdering.
- Keith Allen: People using a public platform to further their own personal agenda, I think that's immoral. You have no right to do that. Tony Blair is a great example of that.
- Keith Allen: Snobbery I hate. And ignorance.
- Keith Allen: (on his favourite band, UB40) I'll take anyone to task about UB40. They were as important as Bob Marley in getting reggae into the consciousness of British youth at that time. I'm proud to be their number one fan.
- Keith Allen: (concerning his notorious reputation) Obviously I have propagated the occasional myth about myself, because the real me, I'm not worth knowing. I'm actually a rather dull man.
- Keith Allen: I'm similar to Marmite in many respects. People either love me or hate me. Why would they hate me? Oh, you know: arrogant cock. All that kind of stuff.
- Keith Allen: (on his role as the Sheriff of Nottingham) The sheriff is a sociopath, utterly asexual, devilishly charming and very politically ambitious.
- Keith Allen: Vanity takes a lot of work. I'm too lazy to be vain.
