The title refers to the almost never seen father of Bret and Bart Maverick, Pappy, who is played by the much younger James Garner and is the source of all the wisdom spouted by Bret and Bret. "Like my old Pappy always said..."
Pappy says that he only raised two children. However, at the end of season four, we are introduced to a third Maverick brother, Brent.
Jack Kelly played Beau 'Pappy' Maverick 's brother Bentley Maverick.