According to ComicBook.com, it hasn't been confirmed if McManamon's Karlo will appear as Clayface on the hit series, or simply as his alter ego.
McManamon's initial casting was announced at WonderCon last year.
A veteran villain in Batman's Rogues Gallery, the original Clayface debuted way back in 1940's "Detective Comics" #40, by Bill Finger and Bob Kane. Fans likely recognize Clayface the most from his appearances on "Batman: The Animated Series," where he was voiced by Ron Perlman. Most recently, the character appeared in the "Legends of the Dark Knight" digital-first series.
"Gotham" airs Mondays at 8/7c on FOX.