Back in the 1960s, the Justice League fought an alternate world team of villains who mirrored the powers of the JLA, with Wonder Woman's opposite number being Superwoman. They engaged in a brief but pretty good fight (back then, DC seemed to go to great lengths to have WW avoid actually fighting a villain physically, unless it was a robot or monster or somesuch...I guess they thought it wasn't properly ladylike). Sadly, no one ever saw fit to revive Superwoman as an ongoing nemesis for Wonder Woman in her own book. There's a new version of Superwoman now, but like most women in comics these days, she's portrayed as little more than a sadomasochist bondage queen. Haven't comic book writers and artists ever dated real girls? LOL
Anyway, I've always thought that for the 70s TV show, Jaclyn Smith would have made a nefariously great Superwoman. Just picture that husky voice and arched eyebrow taunting Princess Diana before they brought the roof down in a slobberknocker fight!