4. Michael Cassidy
Smallville Role: Grant Gabriel/Julian Luthor (7 episodes, season 7)
DCEU Role: Jimmy Olsen (Batman v Superman: Dawn of Justice)
You may remember Michael Cassidy from his recurring Smallville role as Grant Gabriel, the young editor-in-chief of the Daily Planet who turns out to be a clone of Lex’s little brother Julian. You may have missed him in Batman v Superman, though, in which he briefly turns up as an ill-fated version of Superman’s pal Jimmy Olsen (who’s an undercover CIA agent in this universe).
3. Marc McClure
Smallville Role: Dax-Ur (1 episode, season 7)
DCEU Role: Officer Ben Sadowsky (Justice League)
OK, Marc McClure’s role in both of these productions is clearly because of his portrayal of Jimmy Olsen in the original Superman movies. Still, we’re counting him as a Smallville actor. He turned up on the show as a kindly Kryptonian hiding away on Earth who was sadly murdered by Brainiac. In Justice League, McClure appears as a cop at the prison of which Barry Allen’s father Henry is an inmate.
2. Alessandro Juliani
Smallville Role: Dr Emil Hamilton (14 episodes, seasons 8-10)
DCEU Role: Officer Sekowsky (Man of Steel)
Appearing throughout Smallville‘s last three seasons, Alessandro Juliani is a memorable addition to the cast as Dr Emil, the League’s resident medical man. It must surely be an in-joke, then, that he was cast as Officer Sekowsky in Man of Steel – who shares several scenes with… Dr Emil Hamilton (here played by Richard Schiff)!