Johnny Galecki is a Belgian-born American actor, best known for his roles as David Healy in Roseanne, Rusty Griswold in National Lampoon's Christmas Vacation, and as Leonard Hofstadter in The Big Bang Theory.
Batman forms Justice League Dark, a new team of dark arts specialists that is led by John Constantine. The team must unravel the mystery of a supernatural plague and contend with the rising, powerful villainous forces behind the siege.
