WMG / James Dean

Warner Bros. assumed James Dean was gay.
When he was getting big, the studio he signed with paired him up with Rock Hudson and Tab Hunter as "eligible bachelors" whose "film rehearsals are in conflict with their marriage rehearsals". Today it's well-known that Hudson was, and Hunter is, gay. Their PR trick might have been extended to Dean on that assumption.

Today it is known that Dean had sex with at least one man. But he also had affairs with women. Whether he was gay or bisexual, obviously, will never be known.