Vanessa (Greeks Bearing Gifts)

Vanessa, previously known as Vincent, was a friend of Jack Harkness. According to Jack, Vanessa was once a "regular guy", who had a girlfriend and liked beer. Jack told Toshiko that Vincent disappeared for a couple of months, and upon return asked to be called Vanessa. "Since then I've always been a little nervous when a friend behaves out of character." (TV: Greeks Bearing Gifts)

Behind the scenes
In the real world, Vanessa would likely consider herself transgender. Jack uses he/him pronouns in his anecdote, while trans women tend to use she/her pronouns, in line with their gender. Toby Whithouse, who wrote the script to Greeks Bearing Gifts, also used he/him pronouns in reference to a presumably trans female horse, Susan, in a comedic line delivered by the Eleventh Doctor in A Town Called Mercy. Both have been construed by some fans as being transphobic.