Since, generally, art imitates life, let's list the heterosexual fictional serial killers!
Karl Arnold (Criminal Minds, Season 1)
Frank Brightkopf (Criminal Minds, Season 2)
The Angel Maker (Criminal Minds, Season 4)
Adam/Amanda Jackson (Criminal Minds, Season 4 -- she counts, even though she has a dick; Adam had no part in the murders)
George Foyet (Criminal Minds, Seasons 4-5 -- though he might have made an exception for Hotch)
The prostitute from "Pleasure is My Business" (Criminal Minds, Season 4)
Henry Grace (Criminal Minds, Season 4)
The killer from "From Cradle to Grave" (Criminal Minds, Season 5)
Ian Doyle (Criminal Minds, Season 6)
And those are just the CM ones I can think of off the top of my head who actually count as serial killers.
Beyond CM, we have:
Howard Epps (Bones, Seasons 1-2)
Francis Dolarhyde (The Red Dragon)
Hannibal Lecter (The Red Dragon, The Silence of the Lambs, etc.)
Again, only the ones I can name immediately.
So there.
(by the way, Criminal Minds has about one or two gay/lesbian UnSubs per season. There have been 6 seasons, so even at the most, that's 12/130, or less than 10% overall, which seems about in proportion with the general population of the earth.)