Captain Charles Ridgely III (1733–1790) was a colonial Maryland planter and ironmonger.
Ridgely was born in Maryland in 1733 to Colonel Charles Ridgely II and Rachel Howard. With his father and brother, he established the Northampton Iron Works just north of Towson, Maryland, under what is now Loch Raven Reservoir. He married Rebecca Dorsey, the daughter of Caleb Dorsey, an ironmonger in Anne Arundel County.
Ridgely built the massive Hampton Mansion between 1783 and 1790. By the time it was completed, the Georgian-style structure was the largest private home in the country. The Mansion is now preserved as the Hampton National Historic Site.
Capt. Ridgely died in 1790. His nephew, Charles Carnan Ridgely, became the second master of Hampton and eventually governor of Maryland.