The Dragon Quest fighter released for Super Smash Bros. Ultimate in July 2019 was Hero. “Hero” is a collective fighter representing four Dragon Quest protagonists: the Luminary from Dragon Quest XI, Erdrick from Dragon Quest III, Solo from Dragon Quest IV, and Eight from Dragon Quest VIII.
Hero was the second character in Ultimate’s first Fighters Pass, following Joker from Persona 5. He arrived with the Yggdrasil’s Altar stage, music from Dragon Quest games, and a command-selection mechanic that gives him a broad but partly randomized set of special moves.
A common mix-up is treating Hero as one specific named character. In Smash, “Hero” is the official fighter name, while the four protagonists appear as alternate appearances. The character’s July 2019 release also predates Banjo & Kazooie, Terry Bogard, and Byleth in the first pass.