Origin

A spirit eternal in mortal form equal to Captain Marvel, Oggar was a student of Shazam around 3000 years ago. From him he learned many powerful magics, but in time the wizard discovered Oggar's innate evil. Like other heroes and deities, Oggar had a place in Shazam's pantheon, styling himself "Shazamo"--but, cursed by Shazam, Oggar could cast spells once only; and he went cloven-hoofed, the mark of an evil god. His hooves bound mortals to "the Cult of the Curse"...the penalty for apostasy: to be driven mad.    
 

In the present

In our time Oggar seeks to restore the ancient Egyptian and Hellenic civilisations, and his own curse; but four alone has he recruited, madmen all, under the delusion that they are respectively: Julius Caesar, Samson, the emperor Nero, and Napoleon Bonaparte. Captain Marvel opposes Oggar, hoping to find his mortal weakness. Though a great sorceror, Oggar's magic may not be cast upon a female; for this reason, Mary Marvel has been often called to stand against him.