So I was actually surprised at the caliber of the Harley Quinn cast.
Kaley Cuoco (big bang theory, Charmed) as Harley
Wanda Sykes (Wanda at large) as queen of fables
Jason Alexander (Seinfeld) as Sy Borgman
Christopher Meloni (Law and order SVU, happy) as commish Gordon
Alan Tudyk (Doom Patrol) as clayface and joker
Giancarlo Esposito (breaking bad) as Lex luthor
The thing is I would have bet that it was Kristen Schaal (Louise belcher on bobs burgers) who was voicing Harley. That grating fry that sometimes comes out sound very similar to me, which was just kind of delightful