(All-Star Comics 001, 1940)
A couple of magic users, Beldame Gaffy (curse-caster) and Trygg (necromancer) team up to steal the lands that rightfully belong to Trygg's niece and nephew so that he could get rich via a zombie-staffed mining operation. Things go well until Hawkman shows up to explode them to death. Also, these are the first (only?) Welsh super-villains we have (will ever?) encountered!
Ordinarily in a two-person set-up like this I would designate one as the boss and the other as a lieutenant or minion but Gaffy and Trygg really do seem like an equal partnership. Sadly however, only Trygg has made any subsequent appearances, specifically in the 2000s-era Hawkman series. I guess it makes sense that the necromancer would be the one to return from the dead but one must nonetheless mourn the dearth of Beldames in this modern world.