 Writer John Byrne rewrote the Superman mythos, again reducing Superman's powers, which writers had slowly re-strengthened, and revised many supporting characters, such as making Lex Luthor a billionaire industrialist rather than a mad scientist, and making Supergirl an artificial shapeshifting organism because DC wanted Superman to be the sole surviving Kryptonian.Carlin was promoted to Executive Editor for the DC Universe books in 1996, a position he held until 2002.K.C.