Suggestions by @tylercollins1

Ralph Fiennes

as Anthony Ludgate in The Squadron Supreme

Kiefer Sutherland

as Henry Gyrich in The Squadron Supreme

Sean Gunn

as Random Person in James Gunn's Scooby-Doo (show)

Tim Curry

as Hallow-Rama Intercom Voice in James Gunn's Scooby-Doo (show)

Neil Fanning

as Scooby-Doo in James Gunn's Scooby-Doo (show)

James Gunn

as Producer in James Gunn's Scooby-Doo (show)

James Gunn

as Writer in James Gunn's Scooby-Doo (show)

Frank Welker

as Scooby-Doo in James Gunn's Scooby-Doo (show)

Zendaya

as Catwoman in DCU by James Gunn and Peter Safran

Amy Johnston

as Harley Quinn in DCU by James Gunn and Peter Safran

Aaron Schoenke

as The Joker in DCU by James Gunn and Peter Safran

Kevin Porter

as Batman in DCU by James Gunn and Peter Safran

Michael Madsen

as Harvey Bullock in DCU by James Gunn and Peter Safran

Jai Courtney

as George "Digger" Harkness in DCU by James Gunn and Peter Safran

Zendaya

as Komand'r in DCU by James Gunn and Peter Safran

Joseph Fiennes

as Brainiac in DCU by James Gunn and Peter Safran

Djimon Hounsou

as Mamaragan in DCU by James Gunn and Peter Safran

Dwayne Johnson

as Teth-Adam in DCU by James Gunn and Peter Safran

Antje Traue

as Faora Hu-Ul in DCU by James Gunn and Peter Safran

Sean Gunn

as Julius Day in DCU by James Gunn and Peter Safran