•
Kelsey Grammer as Gary "The Rat" Andrews, a successful and ruthless lawyer at Harrison, Camille, Beckett and Weiss who has turned into a 6-foot rat. According to the episode
This Is Not a Pipe, Gary likes opera. •
Billy Gardell as Jack Harrison, Gary's boss and named partner at Harrison, Camille, Beckett and Weiss. •
Betty White as Gary's Mother, unseen and only appears as a voice on the telephone. •
Robb Cullen as Johnny Bugz, a pest exterminator with a particular dislike of rats and pet cat called Boots. •
Brooke Shields as Cassandra Harrison, Mr. Harrison's wife. She only appeared in the episode
Future Ex-Wife. •
Camille Grammer as Betty, Mr. Harrison's Secretary •
Spencer Garrett as Truman Pinksdale, President of the Montana Resident's Committee. •
John Mahoney as Steele, resident at the Montana apartment building. •
David Hyde Pierce as Addison, resident at the Montana apartment building. •
Rick Gomez as Bud, a cheese delivery boy who is not very bright and mistakes Gary for being a dog. •
Hynden Walch as Little Girl, witness in the Southern Tobacco Company case. •
Ted Danson as Terry McMillian, con artist and suck up, joins the firm as their newest mergers and acquisitions lawyer. •
Mary Stuart Masterson as Caroline Swanson, Gary's ex-girlfriend and an opposing lawyer. •
Wayne Knight as Gary's rival, J. P. Wordley. •
Joe Pantoliano as Anthony 'the Heel' Stilletto •
John Corbett as Frank Spillogotoriettio, lawyer with Boywe, Cheatem and Howe. He only appeared in the episode
This Is Not a Pipe. •
Michael Keaton as Jerry Andrews, Gary's cousin and con artist, wanted for forgery, polygamy and other offenses. •
Vance DeGeneres as Additional Voices • Susan Savage as April • Jonathan David Cook •
Seymour Cassel • Marnie Alexenburg •
Robert Goulet as Himself •
Kristin Bauer van Straten •
Rob Paulsen as Police Officer •
Kevin Michael Richardson •
Michael Panes ==Media==