Suggestions by @luisperezcozar

Michael Rosenbaum

as The Flash/Wally West in Scooby-Doo! & Justice League Unlimited

Flash (DCAU)

as Flash/Wally West in Scooby-Doo! & Justice League Unlimited

John C. McGinley

as The Atom in Scooby-Doo! & Justice League Unlimited

Jeffrey Combs

as Question in Scooby-Doo! & Justice League Unlimited

Gina Torres

as Vixen in Scooby-Doo! & Justice League Unlimited

Jennifer Hale

as Ice in Scooby-Doo! & Justice League Unlimited

Maria Canals-Barrera

as Fire in Scooby-Doo! & Justice League Unlimited

Kevin Michael Richardson

as Mr. Terrific in Scooby-Doo! & Justice League Unlimited

Billy West

as Skeets in Scooby-Doo! & Justice League Unlimited

Tom Everett Scott

as Booster Gold in Scooby-Doo! & Justice League Unlimited

Amy Acker

as Huntress in Scooby-Doo! & Justice League Unlimited

Morena Baccarin

as Black Canary in Scooby-Doo! & Justice League Unlimited

Kin Shriner

as Green Arrow in Scooby-Doo! & Justice League Unlimited

Giselle Loren

as Stargirl in Scooby-Doo! & Justice League Unlimited

Phil LaMarr

as Static Shock in Scooby-Doo! & Justice League Unlimited

Phil LaMarr

as S.T.R.I.P.E. in Scooby-Doo! & Justice League Unlimited

Jennifer Hale

as Zatanna in Scooby-Doo! & Justice League Unlimited

Kevin Conroy

as Crimson Avenger in Scooby-Doo! & Justice League Unlimited

Phil LaMarr

as Steel in Scooby-Doo! & Justice League Unlimited

Daniela Bobadilla

as Miss Martian in Scooby-Doo! & Justice League Unlimited