Here are picks.
Billy Zane as Lex Luthor.
Known for: Tombstone (1993), Demon Knight (1995) and Zoolander (2001).
Reason: Well he looks the animated series version. After watching Demon Knight he can play a charismatic figure but in the shadows some who is cold and maniacal/terrifying figure. Not to mention his voice sounds like Clancy Brown.
Jessica Biel as Mercedes "Mercy" Graves.
Known for: Texas Chainsaw Massacre (2003), I Now Pronounce You Chuck and Larry (2007) and The A-Team (2010).
Reason: She looks the part and can act the part. She's very attractive and can do great action. I mean she's played a toughie before.
Terence Stamp as Alfred Pennyworth.
Known for: Superman II (1980), Star Wars Episode I: The Phantom Menace/Bowfinger/The Limey (1999) and The Adjustment Bureau (2010).
Reason: I know he was Zod in Superman II. Chris Evans was Human Torch and Captain America so why not? He's a great/underrated British actor who can be warm/kind and at the same time he can also be a bad ass. I think he would do an amazing job.
Bryan Cranston as Commissioner James Gordon.
Known for: Malcolm In The Middle (1999 - 2005), Breaking Bad (2008 - 2013) and Batman: Year One (2011).
Reason: Cranston deserves to play Gordon in live action. Not to mention he looks like him. He's a terrific actor and he can do anything.
Let me know what you think? If you disagree please be respectful.