Can you play gta online solo or with a single character?

Quick Answer
Yes, Grand Theft Auto Online can be played solo; you control a single character and can explore the world alone, even though the game is primarily an online multiplayer experience.
Explanation
Grand Theft Auto Online is the online component of Grand Theft Auto V, released in 2013 for PlayStation 3 and Xbox 360 and later for other platforms. The game supports up to 30 players in a shared open world set in the fictional state of San Andreas, which includes the city of Los Santos. Players create and control a customizable silent protagonist who can roam the countryside or city, engage in missions, or simply explore. While the core design encourages cooperative or competitive play with other online users, the game does not require additional players; a single player can log in, spawn their character, and play alone. Solo sessions allow the player to complete missions, build businesses, and experience the game’s content without interacting with other human players, although the environment remains a shared online space that may contain other players’ characters. Thus, GTA Online is playable solo, but the experience is fundamentally rooted in an online multiplayer framework.