In the 'Class Reunion' episode (Season 3, episode 19 - viewable in reruns and Amazon Prime) of 'The Andy Griffith Show' which first aired February 4, 1963, two shots of Andy's and Barney's high school yearbook reveal their full names.

Bernard Milton (Barney) Fife (Don Knotts) is a high-strung, overly enthusiastic but bumbling deputy to Sheriff Andy Taylor (Andy Griffith) in the fictional small town of Mayberry. His tendency to become unnerved under stress prompts Andy to issue Barney only one bullet for his revolver, and he is required to carry it in his shirt pocket.

Jesse Donald Knotts was a legendary American comic actor who won five Emmys for his portrayals of Barney Fife. He also appeared in several movies and in the TV series 'Three's A Crowd'. He was born in West Virginia July 21,1924 and passed away from lung cancer in Los Angeles February 24, 2006.

His additional movie credits include 'The Incredible Mr. Limpet' (1964), 'No Time for Sergeants (1958), 'The Apple Dumpling Gang' (1975), and on TV 'Three's Company' (1977-1984).

More Info: mayberry.fandom.com