The characters controlled by players are often termed Player Characters.
In WildStar players can create up to 6 player-characters per realm, which are independent, but can only be played 'one at a time'. Players create and enter the game with a character, and where they then join and interact with the game world. In order to play different character, a player can "log out" of the current character, by clicking 'Switch Character' on the 'Esc menu', exiting them from the realm's game world. They can then pick or create another character to play, and then re-enter the realm again.