Critical Role is a show where a group of voice actors play Dungeons & Dragons on a livestream. While the show has had a core cast of eight throughout both of its campaigns, with Matthew Mercer serving as Dungeon Master, there have also been a number of guest stars over the years. Most of these have just been one offs, though a few have made multiple appearances. Here's a list of all of them.
Campaign 1: Vox Machina's Friends and Companions
Zahra Hydris, played by Mary Elizabeth McGlynn (ep. 18-19, 43-45, 57-58, 65, 70, 78, 81 and 114-115) - A red tiefling warlock, Zahra was first assigned to work with half of Vox Machina during the famous Trial of the Take episodes. She played a major role in the Chroma Conclave arc, eventually distracting two fire giants alongside her love interest, Kashaw, in order to help Vox Machina make it to Thordak, the Cinder King. McGlynn is one of just a handful of guest stars to make multiple, non-consecutive appearances on the show, with her character playing a role in different parts of the story.
Lyra, played by Felicia Day (ep. 18-19) - A goofy and nerdy wizard, Lyra was only in the Slayer’s Take on a technicality, but she proved herself in a battle against the white dragon, Rimefang. Memorably, she often confided in Scanlan about her unrequited love for an adventurer named Aldor.
Kashaw Vesh, played by Will Friedle (ep. 20-21, 43-45, 58, 65, 73, 78, 81 and 114-115) - A heterochromic human cleric whose god is also his evil wife, Kashaw is a relentless cynic and a paragon of sarcasm. Originally part of the second Trial of the Take group, Kashaw eventually aided the party alongside Zahra in the Siege of Emon and the Attack on Vecna. Zahra and he are expecting a child.
Thorbir Falbek, played by Wil Wheaton (ep. 20-21 and 42) - A dwarven fighter with a luckless streak known to many (out of game) as the Wheaton Curse. He's a long-serving member of the Slayer's Take and a caring father to a young girl.
Lillith Daturai, played by Kit Buss (ep. 25) - A quiet and intelligent white tiefling illusionist, Lillith aided Vox Machina in their fight with the Briarwoods. She is Zahra's cousin.
Garthok, played by Jason Charles Miller (ep. 41-42) - A half-orc rogue, Garthok is a member of the Clasp, a guild of thieves and assassins. He turned his back on Vox Machina when they rejected Spireling Shenn's deal to establish a Clasp network in Vasselheim.
Gern Blanston, played by Chris Hardwick (ep. 46) - A blue dragonborn necromancer with a heavy Scottish accent, Gern is a self-proclaimed candle maker whose candles are enchanted with spells. He travels with a retinue of his undead thralls. His flying broom was stolen by Vex’ahlia, starting "broom-gate," which led to some interesting debates around player-to-player theft.
Shale, played by Chris Perkins (ep. 55) - An elderly goliath fighter from Grog’s old tribe. She only has one eye and one hand but that didn’t stop her in helping Vox Machina slay the black dragon, Umbrasyl.
Kerrek, played by Patrick Rothfuss (ep. 56, 81-84)- A kind and wise human paladin from Westruun, Kerrek is a de facto leader of Westruun refugees. After adventuring from some time, Kerrek retired and turned to blacksmithing until Westruun was destroyed by the Chroma Conclave. Kerrek returned and helped the party slay the cunning green dragon, Raishan, unexpectedly striking the killing blow.
Tova, played by Noelle Stevenson (ep. 92-93) - A dwarven blood hunter and a were-bear, Tova adventured to the Nine Hells with her friends. She and two others survived and were imprisoned in the City of Dis by the pit fiend Utugash, whom she killed with the help of Vox Machina.
Lionel Gayheart, played by Jon Heder (ep. 99-101) - A half-orc multiclassing in bard and barbarian, Lionel was hired muscle for Scanlan Shorthalt’s alter-ego, the "Meat Man." He uses the Totem of the Duck barbarian homebrew subclass. He eventually became the Backup Field Commander of the Darrington Brigade.
Sprigg, played by Darin De Paul (ep. 105-106) - An elderly arcane trickster gnome, Sprigg ran away when his evil adventuring party was killed by hobgoblins. After living in shame for thirty-seven years with an imp companion, Sprigg eventually became a Steward of Ioun -- but not before imparting Vox Machina with some elderly wisdom.
Arkhan, played by Joe Manganiello (ep. 113-114) - A neutral evil dragonborn paladin/barbarian, Arkhan is a follower of Tiamat. He aided Vox Machina in the fight against Vecna, but instead of destroying the Hand of Vecna, stole it for himself in the name of his Queen.
Campaign 2: Allies of the Mighty Nein
Shakäste, played by Khary Payton (ep. 7, 29, 62 and 70) - A wild-haired human cleric with white hair and eyes. His familiar is named Grand Duchess Anastasia Nikolaevna and originally took the shape of a hummingbird. Since Mighty Nein’s assistance in free gnoll captives, he has been a friend and ally to them.
Calianna, played by Mark Hulmes (ep. 21) - A half-elf sorcerer with half of her face covered in black dragon scales. She was a former follower of Tiamat and a member of the Cult of the Caustic Heart in Port Dimali. The Mighty Nein helped her destroy a magical bowl that allowed the cult to contact Tiamat.
Keg, played by Ashly Burch (ep. 26-30) - A dwarven fighter and former member of the Iron Shepherds, she helped the Mighty Nein defeat her former employers at the cost of Mollymauk’s life. She and Beau shared a tryst.
Nila, played by Sumalee Montano (ep. 27-28) - A kind and gentle firbolg druid, Nila was looking for her partner and her son who were both imprisoned by the Iron Shepherds. After freeing them, Nila promised Caduceus that her clan would take care of the temple in the Blooming Grove.
Twiggy, played by Deborah Ann Woll (ep. 45) - A gnome arcane trickster, Twiggy was a stowaway on the Squall Eater. She possessed the Heirloom Sphere, which transported the Mighty Nein and Twiggy to another dimension: The Folding Halls of Halas. Twiggy helped the Mighty Nein fight a dragon there and escape the sphere.
Spurt, played by Chris Perkins (ep. 50) - A young kobold inventor, Spurt originally meant to spy on the Mighty Nein but joined them at the promise of food. In a Fire Giant citadel, he was killed by a giant’s hammer. So far, Perkins is the only guest star to appear in both campaign, playing different characters in each.
Reani, played by Mica Burton (ep. 74-76) - An aasimar druid, Reani follows her angelic guide Samliel without question. She revealed that she is the Lightbringer, a superhero known around the city of Uthodurn. She helped the Mighty Nein find and fight the white dragon Gelidon.