If you’ve never heard of the character before now, you’re not alone. It appears that DC is digging deep to keep up with Marvel’s extensive two-year movie list.
Black Adam began as a hero who was given powers by the ancient Egyptian wizard Shazam. However, the powers corrupted him and Shazam banished Black Adam from Earth. When he returned from outer space in modern times, he was tricked into speaking the magic words that relinquished his powers and forced 5,000 years of aging on him all at once.
Since his first appearance, he was rebooted as an anti-hero who was noble and well-meaning, but had a notable anger problem. He was a main member of The Justice Society of America until he received his own series in 2007.
Dwayne Johnson stated that Black Adam was always one of his favorite characters, and he was quite fond of anti-heros in particular. This comes as no surprise that Johnson was cast as Black Adam, as he played another Egyptian role in The Mummy spin-off The Scorpion King.