In 1997, when Amalgam Comics were still a thing (Amalgam Comics being a joint venture between Marvel and DC which saw a number of key characters from each company merge to create new characters), one of the mergers saw Superman and Captain America become "Super Soldier". Of course, Super Soldier needed an enemy, so Amalgam made one out of the two heroes' main villains, Lex Luthor and Red Skull. The resulting being was called Green Skull AKA Alexander Luthor - a corrupt war profiteer who was aiding the Nazi Party in an effort to prolong the war, but who was masquerading as an entrepreneur and philanthropist. He used a serum of his own creation - made from a radioactive ore known as "Green K" - to halt his ageing process, but it also resulted in him having a hideous green appearance.
