Someone who has a particular regard for someone or something
he was a great admirer of Mark Twain
A man who is attracted to a particular woman or a woman who is attracted to a particular man
she's got a secret admirer
supporter: a person who backs a politician or a team etc.; "all their supporters came out for the game"; "they are friends of the library"
a person who admires; someone who esteems or respects or approves
a non-trans person who is attracted to trans-people. They are often courted by trans venues, which advertise nights for trans people and their admirers, in fact the trans venues require them, as they usually buy the drinks.