There are various characters who have called themselves Superwoman, but they are usually an older female counterpart of Superman as opposed to the younger one of [[Supergirl]]. 

Those that have called themselves Superwoman were [[Lois Lane]] (both a good and evil version), a gender-bent Superman, a future descendant of Superman's pal Jimmy Olsen, an obsessed Superman fan, and Lois Lane's sister. As Superwoman is an somewhat obscure character, the variation most commonly seen in fanart is a gender-bent Superman.
superwoman