Re: James Spader is Ultron!
I had not heard of the man before the casting announcement, or seen any of his programs. However, I trust Marvel's judgment in the matter: they have had a flawless record with the MCU.
Justice League (TBD)
Batman: Ben Affleck. Superman: Henry Cavill. Wonder Woman: Gal Gadot. Green Lantern: Tom Anderson.Darkseid: Michael Cera.
Aquaman: Alexander Skarsgard. Martian Manhunter: Liam Neeson. The Flash: Neil Patrick Harris.