Do you want to compare John Constantine with Sgt. Rock? Discover the powers, weakness & weapons of John Constantine and Sgt. Rock from John Constantine Biography and Sgt. Rock Biography. Find out all about John Constantine and Sgt. Rock.# Check out how is John Constantine unique and distinct from Sgt. Rock. Discover their love interest, sidekicks, family tree and the movies and games list in which John Constantine and Sgt. Rock have appeared. Find out everything about them here!