8Iceman
Way back when X-Men were originally introduced (1963), they consisted of Cyclops, Beast, Angel, Marvel Girl, and Iceman. Over the years Iceman went through a lot of looks and a few relationships, but the most important storyline was from 2015 when a time-displaced teenage version of Iceman was introduced, and psychic Jean Grey discovered he preferred men company. The Iceman never showed his orientation especially in the comics from 1960 to 2015, but after a long talk with his teen self, Iceman confided that it was too hard for him to cope with being both a mutant and someone that prefers the same gender. But since he had to deal with his powers openly, he suppressed his own desires to the point where he refused to even think about it. This was basically the point where the comic world just received the intensely powerful character who is also interested in the same gender.