In "This Little Piggy", Batman (Kevin Conroy) and Wonder Woman (Susan Eisenberg) run afoul of Circe (guest star Rachel York), who turns Diana into a pig, prompting the Dark Knight to call on a former flame, Zatanna (Jennifer Hale), for help in restoring Wonder Woman to normal.
As you already know, Conroy made his singing debut in this episode, with a cover of Cole Porter's "Am I Blue". York performs "Lulu's Back in Town".
Scintillating. Sublime. Divine. 'Nuff said.