The Legend of Vox Machina features a familiar face in every episode, although newcomers to the franchise might not recognize him. While the new Prime Video series focuses on the bawdy and resourceful adventuring group Vox Machina, viewers may have noticed that another character keeps reappearing in every episode as well. This long-haired male elf has appeared in each episode, occasionally suffering a grisly fate in the process. If you've watched Critical Role, the popular web series that The Legend of Vox Machina is adapted from, you probably recognize that the animators have put cast member Matt Mercer in every episode, a nod to the role that Mercer plays in the series itself. Mercer has appeared as an in-show character in all six episodes to date, either as a guard, a zombie, or as a (doomed) resistance member wearing an eyepatch. You can see a few of his appearances throughout the series below:
The cameo appearances by Mercer (who also voices himself and several other characters in the series) is a nod to Mercer's role in Critical Role. Mercer serves as the Dungeon Master of Critical Role's Dungeons & Dragons campaign, responsible not only for guiding the rest of the cast in their adventures, but also bringing life to the wider world of the show. Not only did Mercer create Exandria, the world that The Legend of Vox Machina takes place in, he also plays all the NPCs in Critical Role, many of which also appear in The Legend of Vox Machina.
While The Legend of Vox Machina brought in a number of guest stars to help Mercer out in the animated series, he still voices multiple minor characters (including himself) in each episode. Mercer also voices Sylas Briarwood, the vampire who serves as one of the primary antagonists of the series. We'll note that Mercer is also canonically a Dungeons & Dragons NPC who appeared in official D&D artwork and also has his own miniature produced by WizKids. The man has a very popular face and his power seems to grow with each new variant that appears in various forms of media.
The Legend of Vox Machina is now available on Prime Video. New episodes are released every Friday.