Factions that non-admin or V.I.P. users can be part of can be found here.
“The Brute Bloodpack is one of the main factions that the player can join. The faction is unique...Brute Bloodpack
“"Branch of the UNSCDF that is responsible for land-based military operations, as well as the...5th Marine Expeditionary Unit
“Recruits are the first faction all new players are assigned to when they first connect to the...Recruits
“The UNSC Provosts Corps (Also known as Military police, Provosts or MPs), are concerned with law...Military Provost
“"Branch of the UNSCDF responsible mostly for naval operations in space, though they sometimes...Navy