Les Garcons (La Notte Brava, 1959), an adaption of Pasolini's novel Ragazzi di vita, follows the exploits of a gay-vague criminal couple (Brialy, Laurent Terzieff).
Une femme est une femme (A Woman is a Woman, 1961): Brialy's girlfriend wants a baby, but he isn't ready, so he enlists the aid of his best buddy (Jean-Paul Belmondo).
Cheri (1962): The bisexual male prostitute from the Colette novel.
L'oiseau rare (The Rare Bird, 1973): a gay-vague waiter gets involved with the problems of his customers.
Robert et Robert (1978). The two Roberts form a bromance while trying to find heterosexual partners through a computer dating service run by the gay-vague Brialy.
La nuit de Varennes (1982): during the French Revolution, a gay-vague hairdresser encounters the legendary lover Casanova (Marcello Mastroianni) and American patriot Thomas Paine (Harvey Keitel).
The Innocents (1987): In his most overtly gay role, Brialy plays a German composer whose son is having an affair with his favorite male prostitute.
By the way, he's written several interesting books available on Amazon France, such as Les Pensées les plus drôles des acteurs.
See also: Colette's Cheri: A Male Prostitute Finds Love.