There is a large cast of ensemble characters voiced by a wide variety of ensemble cast members. Here are some of them:
Philigren the Feared - Administrator of TAG (Episode 1-1, ) Played by Sean Curry
Captain Randy Seesail - Leader of the Dearthwood Collective (Episode 1-1) Played by Vegas Lancaster
Mayor Digby - Mayor of Bel Dale (Episode 1-1) Played by Patrick Lavery
Mayor of Beachhaven - (Episode 2-1) Same guy.
Kai, the Monk - Temporary Party member in Story Arc 1. Played by Andrew Timmes (Episode 1-1, 1-2, 1-3, 1-4)
Rolf the Paladin - Arrogant leader of the Armored Griffins, a rival adventuring group to Party 13. Played by Vin St. John (Episode 1-2)
Lydia the Wizard - lover of pie, the beautiful technical wizard, member of the Armored Griffins. Varne is in love with her, as are most of the rest of Party 13. Lora hates the attention paid to her. Played by Liz So. (Episode 1-2)
Francois - member of Armored Griffins. He has a tremendous moustache. Played by Matt Uhrich. (Episode 1-2)
Kixaras the Summoner - member of Armored Griffins. Played by Lili Timmes. (Episode 1-3)
Bob the Hunter - Member of the Armored Griffins. "The Yin to my Yang" says Thoven Battlebeard. Played by Dave Herman.
Annabelle the Minotaur - former member of The Saviors adventuring party. Has single-handedly saved this plane of existence on six occasions. Voiced by Dave Herman.
Mekar the Wizard - former member of The Saviors adventuring party. Played by Dave Breidenstine. (Episode 3-3). Inventor of the Fire Talk spell. Famous quote: "Magic is my Wife, Husband Father Mother, Son and Daughter"
Tom, the Talking Fish (Episode 2-3) - voiced by the great Vegas Lancaster
Dorgoth, son of Bolgord, the dragon (Episode 2-3) - voiced by either Dan Keyser or Benedict Cumberbatch. (Wikipedia entries can be edited by anyone, people. Let's make this happen!)
Tacomin Gemmin' - Goblin porter/driver of the airship Jester's Paradise (Episode 4-1). Played by Mark Smith. Interestingly, the first Ensemble Character to have an extensive written back story that is incongruently out of place when compared to the centrality of the character to the plot. This can only indicate one of three things: 1. that there is a more central and compelling story arc to come featuring Tacomin Gemmin' in a starring role, 2. that Mark Smith is so dedicated a voice performer that he was unwilling to tarnish the reputation of neither the show nor his own unbesmirched reputation with anything less than a fully immersive interpretation of his 3 lines, or 3. that someone had waaaaaay too much time on his or her hands one afternoon. (Ed. note -- it's likely a combination of 1 and 2. Definitely not 3.)
Allora (Episode 3-3) - also known as “The Enlightened One”, “Holy Avenger”, and “The Big A” - is a God, obviously. Most of the time She's fairly busy with God-Things but occasionally She deigns to lend a Holy Hand to a faithful servant. Mostly because She likes to watch ghost-humans muck about while trying to communicate with their friends. Played by Caroline Collins
Anthony - this guy who did not have something better to do that night all those friends of Rudy's came over.
See also the list of Main Characters.