Captain Jack Harkness
The character is described as both "lethally charming... good looking and utterly captivating", as well as "flirtatious, cunning, clever and a bit of an action man". Within Doctor Who, Jack's personality is  light-hearted, although this changes in Torchwood's first series, where he becomes a darker character. In Torchwood Series 1, Jack has been shaped by his ongoing search for the Doctor and also by his role as a leader, in which he is predominantly more aloof. During The second series of Torchwood, Jack became a much more light-hearted character once again, after appearances in Doctor Who where he was reunited with the Doctor.