Outside of Clark kent/Superman and Bruce Wayne/Batman.....

[The Major]

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[The Major]

Wonder Woman/Diana Prince
Flash/Wally, Jay and Barry
GL/Kyle, John and Hal
GLC
Etrigan the Demon/Jason Blood
Adam Strange
Manhunter/ Kate Spencer
Huntress/Helena Bertinalli
Birds of Prey
L.E.G.I.O.N
Teen Titans
Blue Beetle/ Ted and Jaime
Steel/Henry Irons
Suicide Squad
Checkmate/ Rucka's version
Chase
JSA
Supergirl/Linda Danvers
Green Arrow/Ollie Queen
The Outsiders

This is tip of the iceberg the DCU has to offer.