Several heroes have taken the codename Hourman. The first was brilliant chemist Rex Tyler, who invented a vitamin he called Miraclo. It gave Rex superpowers—but only for one hour. Donning a distinctive caped-and-hooded costume, Rex was a founding member of the Justice Society of America. Unfortunately, he became addicted to Miraclo and was unable to develop a non-addictive version. Rex was almost killed by time-warping villain Extant during Zero Hour, but android Hourman Matthew Tyler switched places to save him.