The Monitor is a powerful being who exists to observe and record the positive matter Multiverse. His assistant Lyla Michaels later becomes the superhero Harbinger. The Anti-Monitor, his evil counterpart in the Antimatter Universe, succeeded in destroying him during the Crisis on Infinite Earths. There was a race of new Monitors born when the Multiverse returned during Infinite Crisis, this time one for every universe. The Monitor was created by Marv Wolfman and George Perez, first appearing in New Teen Titans (Volume 2) #21. (1982)
