Leofric

Derived from Old English leof "dear, beloved" + ric "power; reign; kingdom". A notable historical bearer is Leofric, Earl of Mercia: he was the husband of Lady Godiva, who (legend has it) promised his wife that he would reduce taxation if she rode naked through the streets of Coventry.

Definitely an unusual yet legitimate way to Leo.

Pronounced LEE-oh-frik.