There are many factions on Star Trek Online, but you can only play as three of them. They are the United Federation of Planets , the Klingon Empire , and the Romulan Republic . The player chooses one of these three factions at the start of character creation. Each faction has it's own variety of playable species, though you must purchase some from the C-Store. Once you choose a faction, finish creating your character, and save, you can not change your faction.