Season 1
Eddie Izzard as Mr. Snerz, an arrogant businessman who wants to capture Mr. Jenkins. Snerz can be seen as a caricature of Donald Trump.
Rob Paulsen voices Little Snerz.
Jeffrey Wright as McWinkle, a serious member of the BAD GUYS (Bureau of Animal Defense Glurfsburg Upper Yipville Section) who is on his way to retirement and assigned to a rookie member to be a mentor. Every time something goes wrong, his blue fur turns gray, resulting in him becoming fully gray by Episode 13 due to Gluntz’s antics and Guy and Sam getting away. Despite his gruff persona, he is shown to deeply care for the animals he is assigned to protect.
Jillian Bell as Gluntz, McWinkle's optimistic and easily excited rookie partner. She returns in season 2 as a fully realized B.A.D.G.U.Y.S. agent.
In Season 2, Bell also voices Hayzel, a perky (but also tough-as-nails) Zookian guard, who captures Guy and E.B. and interrogates the two in Season 2, Episode 3.
John Turturro as The Goat, a brutal bounty hunter goat sent by Mr. Snerz. He speaks with a tough Spanish accent. A running gag in the show is that whenever a character is surprised and alerted to his sudden appearance, they yell for example: The Goat is In The... and the scene cuts away to The Goat who proceeds to say I Am In The... .
Dee Bradley Baker as the vocal effects of Mr. Jenkins (credited as "Chickeraffe"), an energetic chickeraffe (big bird with Ossicones) who Guy and Sam protect.
Baker also does the vocal effects of the Giroosters, Squails, Camelopes, Dolphocudas, and all the animal hybrids within the show.
Fred Tatasciore as Yes-Man, Mr. Snerz's sniveling assistant.
Tatasciore also voices Jeremy, Hayzel's "Lie Detector" who helps interrogate Guy and E.B. in Season 2, Episode 3.
Tracy Morgan as Michael (credited as "Fox"), an eccentric yet ravenous fox who is obsessed with green eggs and has a crush on a green chicken named Sandra. Michael is implied and shown to do through self-rehab, creating mindfulness recordings for himself so he doesn’t destroy the chicken coops and to push back his obsession with eggs so he can win Sandra over. Sam however provokes Michael multiple times resulting in Michael relapsing for quick moments at a time only by saying Sandra’s name.
Daveed Diggs as Squeaky (credited as "Mouse"), an imprisoned mouse who wants to feed his wife and daughter. He himself is a cross parody of the character "Jean Valjean" from Les Misérables and Diggs' own characterization of Marquis de Lafayette from Hamilton. He speaks with a French accent, though most are unable to understand his language due to being a mouse as the only intelligible vocalization the characters can understand is a simple “squeak”.
Billy Eichner as Captain Bigman, McWinkle and Gluntz's boss who despite his name is pretty tiny.
David Kaye, Nika Futterman, Keith Ferguson as the Cronies (Crony 3 is credited as "Big Green Crony").
Rob Paulsen as Pool Shark
David Kaye as Joaquin Furmano, a news reporter.(Furmano later appears in Season 2)
Grey Griffin as Ty, Guy-Am-I's niece, a member of Am-I family.
Chris Diamantopoulos as Bean Counter, who works for SnerzCo.
