Angela Lansbury
Mrs. Van Gundy
Madeline Carroll
Janie Popper
Jeffrey Tambor
Mr. Gremmins
Philip Baker Hall
Franklin
Maxwell Perry Cotton
Billy
William Charles Mitchell
Yates
Henry Kelemen
Young Tommy Popper
Dylan Clark Marshall
Young Tommy Popper #2
Brian T. Delaney
Young Tom Popper, Sr. (voice)
Elaine Kussack
Gremmins's Secretary
Harlin C. Kearsley
Town Car Driver
Matthew Wolf
Antarctic Friend (voice)
Andrew Stewart-Jones
Animal Control Guy
James Chen
Fish & Game Officer
Rafael Osorio
Marine & Waterfowl Officer
Curtis Shumaker
Sanitation Officer
Joseph D'Onofrio
Random Man on Street
Betsy Aidem
Tavern Hostess
Chris Beetem
Young Developer
Charles L. Campbell
Old Tom Popper, Sr. (voice)
Daniel Stewart Sherman
Zoo Security Guard
Charlie Semine
Cop #2 (Quint)
Cynthia Kirchner
Pulse Lounge Beautiful Girl (uncredited)