Source: Batman and Superman: World's Finest #9 (1999)
Type: ImpostorKarl Kesel's World's Finest mini-series has a cute bit occurring in Year 9 of the two heroes' careers, which for Superman is when he was dead. So you've got the four Supermen of Reign, and they come across four MORE Superman, all of them impostors and Intergang agents (briefly) getting in on the action.
The first of these is Zzzuperman, whose cover story is that he "evolved to the next Kryptonian life-stage". An electric Superman before there even was such a thing (in the chronology, that is), he quickly surrendered when the Eradicator started throwing his own energies around.