Fantasy Games
Fantasy is the most popular tabletop RPG by a wide margin. Dungeons & Dragons, the progenitor of the hobby, is undeniably the world’s most popular TTRPG by a wide margin. Its sibling Pathfinder is arguably the second most popular TTRPG, and there are many other games that share the distinctive classes-and-levels d20 fantasy approach.
However, there are plenty of other fantasy games built on very different approaches to gameplay and character advancement, with different assumptions about how fantasy worlds operate.