Suggestions by @jamesthethinker

Brendan Fraser

as Firefly in Nightwing and Batgirl

Ludacris

as Ronald Houston in Nightwing and Batgirl

Rainn Wilson

as Calculator in Nightwing and Batgirl

Mark Harmon

as Commissioner Jim Gordon in Nightwing and Batgirl

Jessica Henwick

as Melinda Zucco in Nightwing and Batgirl

Paul Levesque

as Blockbuster in Nightwing and Batgirl

Joe Keery

as Nightwing in Nightwing and Batgirl

Dylan O'Brien

as Nightwing in Nightwing and Batgirl

Madelaine Petsch

as Batgirl in Nightwing and Batgirl

Sophie Turner

as Batgirl in Nightwing and Batgirl

Unknown Dog Actor

as Haley in Nightwing and Batgirl

David Scheunemann

as Production Designer in Nightwing and Batgirl

Ngila Dickson

as Costume Designer in Nightwing and Batgirl

Natalie Holt

as Composer in Nightwing and Batgirl

Duncan Jones

as Director in Nightwing and Batgirl

Andy Griffith

as Jonathan Kent in Casting Every Superman Character

David Hasselhoff

as Adam Westing in Sort by Tropes

Davy Jones

as Adam Westing in Sort by Tropes

Keanu Reeves

as Adam Westing in Sort by Tropes

Leonard Nimoy

as Adam Westing in Sort by Tropes