sexual minority
A phrase used to refer to a person whose sexual orientation is not completely heterosexual. It is typically used as an adjective (i.e. "sexual minority males"). When I worked in the counseling center, many of my patients were sexual minority teenagers.
be in a minority of one
To be alone in a particular interest or viewpoint. If you voted for that candidate, you're in a minority of one in our house.
be in a/the minority
To be in a group that is less than the majority. As the only girl in a house full of boys, I'm definitely in the minority. With those views, you'll be in the minority around these parts.