Peter Davison is a British actor, 1951-present.
Born Peter Moffettn.b. and raised in London, Davison had an early role as the Dish of the Day in the TV adaptation of The Hitchhiker's Guide to the Galaxy (alongside his then-wife Sandra Dickinson, who was playing Trillian), but his breakout role was as vet Tristan in All Creatures Great and Small, the BBC adaptation of James Herriot's beloved memoirs.note
It was this role that brought him to the attention of Doctor Who producer John Nathan-Turner, who was searching for a replacement for outgoing Doctor Tom Baker. Only 29 when he was cast as the Doctor, Davison would be the youngest Doctor until Matt Smith was cast at 26.
Davison played the Doctor's fifth incarnation from 1981 to 1984, following the advice of Patrick Troughton (the actor who played the Second Doctor) to limit his tenure to three seasons to avoid being typecast, and was replaced by Colin Baker. Later on, he returned to the role for Big Finish Doctor Who audios and reprised it onscreen in the Children in Need special "Time Crash". His Doctor remains very popular among the fandom, even if his companions were somewhat annoying, and Davison himself was overshadowed in the collective consciousness by his predecessor. He initially came under fire simply because he was replacing Tom Baker, although it's worth considering this was where the first cracks behind the scenes were starting to show. But as time has passed, the Fifth has been vindicated as one of the most underrated Doctors.
It's also worth noting that Tenth Doctor David Tennant grew up with Tom Baker's and Davison's stories. "Time Crash" is essentially a tribute/love letter to him. Where it touches on why the 10th Doctor always admired the 5th Doctor. However contrary to fan rumors Tennant did not write or have input into the "You were my Doctor" line, and it has been stated that this story was writer Steven Moffat's love letter to the Fifth Doctor (Moffat has often stated that Peter Davison was 'his' Doctor), whereas Tennant has often stated that Tom Baker was 'his' Doctor.
Since leaving Doctor Who, he has appeared as a regular in a number of programmes - despite the page quote, he's probably the only classic series Doctor to really avert I Am Not Spock, and has had a healthy career ever since. These include A Very Peculiar Practice; Holding the Fort; Campion, for which he also sang the theme tune; The Last Detective; Fear, Stress, and Anger; Law & Order: UK; and As Himself in Toast of London. He's also made something of a name for himself as a musical theatre actor, with high-profile roles in Spamalot and Legally Blonde: The Musical. Bizarrely enough, composed and performed the theme music to Button Moon. Yes, that's him singing. In 2013 he wrote, directed and starred in the unofficial Doctor Who 50th anniversary webcast episode 'The Fiveish Doctors.' His wife, their two sons, his daughter Georgia Moffett, and Moffett's two young children also appeared in the webcast, as did many former Doctor Who actors.
His daughter, Georgia Moffett, is also an actress, though she gave up acting in 2012 in order to focus on raising her children, and also to try to become a screenwriter, after being frustrated at the lack of acting work. She has acted with her father several times, including in an episode of The Last Detective, and had a regular role as his on-screen daughter in Fear, Stress, and Anger. She also played his daughter in a different sense on Doctor Who: a female "clone" of sorts made from the Tenth Doctor's DNA. She had a daughter Olive with David Tennant in March 2011, marrying him later that year (they had a second child, Wilfred, in 2013), which makes the Doctor his own father-in-law.