I think that the DCAU Joker's was still up there, I mean despite the Metropolis rocket attack at the end of the STAS episode 'World's Finest', there was his numerous destructive uses of the space-laser in 'Batman Beyond: Return of the Joker', there were also people's corpses littering the place in the background of 'Mad Love' and the Batman the New Adventures episode that had the Harley, Ivy and Clayface segments.
As well as random people in episodes, like the Cadmus guy he gassed in the (chronologically) first Royal Flush Gang episode.