Juggernauts, Divers, and Skirmishers.
Most people talk about champions like Irelia or Riven, but historically champions like Garen and Fiora were considered Bruisers as well. The term basically meant "Fighters that can build defensively if they want to", but some people are using it as a synonym for Duelist, which is also not really a class and just describes the way a given champion fights.
Garen and Darius both fit under the term Bruiser, and both need different things to stay viable, and neither need the same things as someone like Irelia or Fiora, or even Jax. Riot did a surprisingly good job with Conqueror in that every single one of these champions can use the rune effectively, albeit some use it better than others.
Whether or not Conqueror was a good fit for the game is a different discussion, but if Riot's goal was to make a keystone rune that benefited "bruiser" champions they definitely succeeded.