Byleth was announced as a DLC fighter for Super Smash Bros. Ultimate on January 16, 2020. Byleth's primary weapon is the Sword of the Creator, which is used in both sword and whip form for his upward attacks. They are also equipped with Areadbhar for their side moves, Aymr for their down moves, and Failnaught for their neutral moves. Byleth is mostly specialized in distance based combat and a lot of their moves are less effective when the opponent is too close. Byleth has alts referencing Dimitri, Edelgard, Claude, and Sothis, as well as their transformation state for both genders.
Male Byleth's original voice actor was Chris Niosi. However, due to Niosi confirming abuse of several ex-girlfriends, as well as being accused of breaking the non-disclosure agreement, he was recast and replaced by Zachary Aguilar.