Double Dragon — The Brawler That Started It All
Billy Lee, Abobo, and the birth of the beat-'em-up boom.
The original Double Dragon (1988 on NES) kicked off the entire beat-'em-up craze. Billy Lee fights through Abobo and the Black Warriors to rescue Marian, learning new martial-arts moves as you earn experience, an RPG-ish wrinkle that was fresh at the time.
The NES port is famous for a quirk: the main story mode is one player only (a hardware limitation), with two-player relegated to a separate versus fighting mode. It frustrated kids expecting arcade co-op, but the game underneath was still a blast.
Elbow smashes, hair grabs, and Abobo's looming menace. This is the template the whole genre copied.