Suggestions by @thecrimsonpaw

1920s

as “The Places that The Turtles Are Sent To.” in Teenage Mutant Ninja Turtles: Turtles In Time

Ancient Egypt

as “The Places that The Turtles Are Sent To.” in Teenage Mutant Ninja Turtles: Turtles In Time

Spoiler

as “The Places that The Turtles Are Sent To.” in Teenage Mutant Ninja Turtles: Turtles In Time

Tohoru Masamune

as Super Shredder in Teenage Mutant Ninja Turtles: Turtles In Time

Keith David

as Doctor El in Teenage Mutant Ninja Turtles: Turtles In Time

Tighten (Hal Stewart)

as Villains Already in the MultToonVerse in What Should Come in the MultToonVerse?

Garry Chalk

as Eagle King in Hero 108

Wayne Knight

as High Roller in Hero 108

Stephen Graham

as Flying Dutchman in The Tantrum Throwin' Misadventures of Penelope Patterson (Miniseries)

Neil Patrick Harris

as Music Meister in The Tantrum Throwin' Misadventures of Penelope Patterson (Miniseries)

Matthew Rhys

as Diesel 10 in The Tantrum Throwin' Misadventures of Penelope Patterson (Miniseries)

Andrew Laing

as Dr. Strangeglove in The Tantrum Throwin' Misadventures of Penelope Patterson (Miniseries)

Mark Strong

as Lex Luthor in The Tantrum Throwin' Misadventures of Penelope Patterson (Miniseries)

Christian Bale

as Dr. Doom in The Tantrum Throwin' Misadventures of Penelope Patterson (Miniseries)

Jon Hamm

as Hal Stewart/Tighten in The Tantrum Throwin' Misadventures of Penelope Patterson (Miniseries)

Dora Dolphin

as Vicky in The Tantrum Throwin' Misadventures of Penelope Patterson (Miniseries)

Jemaine Clement

as Dr. Claw in The Tantrum Throwin' Misadventures of Penelope Patterson (Miniseries)

Joaquin Phoenix

as Megamind in The Tantrum Throwin' Misadventures of Penelope Patterson (Miniseries)

No Voice

as Feathers McGraw in The Tantrum Throwin' Misadventures of Penelope Patterson (Miniseries)

Brad Garrett

as King Koopa in The Tantrum Throwin' Misadventures of Penelope Patterson (Miniseries)