Also known as a "gayter" (gay-hater), i.e. an anti-gay bigot

Prejudice in the forms of

Specific opposition to an LGBT issue or person.

Also the title of a book by gay author Mark Simpson which criticizes current gay culture.

Homophobia - a fear or hatred of or, more generically, antipathy toward homosexuals

Heterosexism - discrimination against and social intolerance toward homosexuals

An opposition to the broad, perceived gay agenda, which can include same-sex marriage, gay rights and related topics.