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 male pronouns in his anecdote, while trans women tend to use female pronouns, in line with their gender identity. 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.