Matsuo Takahashi (Pat Morita), the original owner	Al Delvecchio (Al Molinaro), Arnold's second owner

Arnold's was the favorite after-school hangout for the students of Jefferson High School including regulars Richie Cunningham (Ron Howard), and his pals Warren "Potsie" Weber (Anson Williams) and Ralph Malph (Donny Most).

Another regular at Arnold's was Arthur "The Fonz" Fonzarelli (Henry Winkler), a cool leather-jacketed motorcycle mechanic and chick magnet who used the men's room at Arnold's as his personal office.

Arnold's was originally owned by Matsuo Takahashi (Pat Morita), a short-tempered, short order cook who flipped burgers for the local teenagers. When he bought the restaurant it was called Arnold's and so to save money, this Japanese-American entrepreneur decided not to rename the restaurant to save on the cost of buying a new sign. Arnold later sold the restaurant to a jovial, easy-going Italian-American named Al Delvecchio (Al Molinaro) who also retained the name of the restaurant.

Joanie and Chachi entertain at Arnold's

When Al's business began to slow, his restaurant suspiciously caught fire and burned to the ground on episode No. 159 "Hot Stuff." The insurance company refused to pay off the claim until Al's worker Chachi Arcola (Scott Baio), admitted he accidentally left an cloth apron on a hot grill after closing for the night.

With the money Al received from the insurance settlement, plus a matching investment from Fonzie (who became Al's partner), Arnold's reopened as "Arnold's...Fonzie and Big Al, Proprietors," a more modern facility now capable of attracting customers (Episode No. 160 "The New Arnold's").

One of the running gimmicks at Arnold's was its juke box. It could be operated with just a bang to its housing, but only The Fonz. knew the secret spot that activated the machine. Everyone else had to use coins to listen to a tune.

TRIVIA NOTE: In the show's first episode, Arnold's Restaurant is called "Arthur's-Drive-In." Later in the series, Arthur "The Fonz" Fonzarelli becomes Al's business partner at Arnold's Restaurant.