Trans-exclusionary radical feminist
A trans-exclusionary radical feminist (TERF) is a feminist that rejects the inclusion of trans women and the problems facing the trans community in the feminist movement. The term was apparently coined by Viv Smythe in 2008.
Their dislike of transgender people stems from misandry. Specifically, they believe that trans men are gender traitors who are leaving the "sisterhood" to oppress women, while trans women are predatory men who wish to engage in violence and sexual assault towards women. Though mainstream feminists often denounce TERFs' transphobia, they rarely acknowledge the group's misandry, probably because they would then be forced to admit that they too hold rampant misandry.