Uncle Marvel

Mary Batson was the sister of Billy Batson and both shared a secret. When either of the two siblings said the word "Shazam!" they were transformed into superpowered beings. Billy was called in his super-powered form Captain Marvel and Mary was called Mary Marvel. The two had many adventures and those adventures Mary recorded in a book she called her Ledger of Good Deeds.

Unfortunately, Mary lost the Ledger of Good Deeds and it was discovered by an elderly but spry old man with last name of Dudley. Dudley was not the most honest of men and after reading the Ledger and discovering all of the secrets of the Marvel Family, Dudley decided to get in on the act himself.

He approached Mary Batson and introduced himself as her Uncle Dudley from California. He explained that he to possessed super powers like the rest of the Marvel Family. He and Mary then shouted Shazam! and when the lightning flash cleared, Dudley stood there in costume, calling himself Uncle Marvel. Dudley had created a set of tear away clothes and torn them off to reveal the costume beneath.

Uncle Marvel possessed no super powers, but never let on that he didn't. He would beg off super-human feats by explaining that his Shazam-bago was kicking up and that he would love to, but just not today. He did attempt to fly once using a rocket pack, but it proved too dangerous so Dudley retired the pack.

The other members of the Marvel Family put up with Uncle Marvel, because he started a company to help others from the moneies given to the Marvel Family by those they helped. This act of charity and goodwill won Uncle Marvel a place in the Marvel Family.

Dudley did have an actual niece who became a friend of Mary Marvel's. She occasionally would dress in a costume similar to Mary's and call herself Freckles Marvel, though she never claimed to have super-powers.