As leader at the Torchwood Institute, Captain Jack is something of a mystery man and likes to keep details of his past in the past.
What we do know is, Jack hails from the 51st century and has vast practical experience of dealing with aliens and is not afraid of tackling dangerous situations. A flirtatious, bisexual charmer, he's usually ready with a flirtatious quip whatever the threat.
Real-life trivia: the racehorse Hucking Harkness was named in his honour.
John, 40, grew up in Joliet, Illinois, but his roots are true blue Scottish: he was born in Glasgow. In his earlier career he was best known to kids as the co-presenter of Live & Kicking on Saturday mornings, and he has gone on to star in several major musicals.
Most recently he appeared as a judge on the BBC's talent search Any Dream Will Do. Outside acting, he likes dogs. He owns two cocker spaniels called Penny and Lewis, which sleep at the foot of his bed. And he's a keen memorabilia collector, owning two TARDISes.
Marriages, divorces, affairs and murders - get the lowdown on all your favourite Torchwood characters.
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