Duval County: William Pope DuVal
Literally, Duval is french for "of the valley".
First territorial governor of Florida
April 17, 1822 to April 24, 1834
DuVal is described by Frank Snyder as a gregarious storyteller that exaggerated his tales to the point of fiction. He writes "His tales were crafted and fabricated with so much skill that his listeners believed every word as the absolute truth. DuVal never hesitated to shade the truth or to embellish his stories so that they became fictionalized account bordering on the fringes of reality."
The former Congressman was appointed by Monroe as the first non-military governor of the territory when Florida officially became a state in 1822. During his twelve year tenure he designated Tallahassee as the capital and established the local court system (DuVal was an attorney by trade).
Another county in Texas is also known as Duval and it's named after his son, Burr Harrison Duval.