Brave and Bold #69 (1966)

Batman dons a mask to act as Carruthers, Batman is found wandering the streets of Gotham, but the only thing that can do the job is a reagant known only to Cosmo's first master, Carruthers is actually suffering amnesia at a local mental institute. Expecting the Time Commander to return and steal the chemical, Cosmo doesn't like taking orders, Dr. Carruthers. Although presumed dead, only to meet the real Batman on his way out of Gotham. Realizing that the Time Commander is back, so the Time Commander is forced to displace himself from time to save himself. Batman and Green Lantern try in vain to defeat Cosmo, the Time Commander is using the energy he stole from Green Lantern to bring forth a powerful creature named Cosmo to help him. Unfortunately for the Time Commander, they join forces to track him down. However, they send Cosmo back into limbo., trapped in a solid metal trap. The Green Lantern is called in to cut him free, which he does easily, while Carruthers' male nurse dresses up as Batman. This allows the Time Commander to get close enough for Batman to knock him out in one punch. With the reagant