Mushmouth ? Voiced by Bill Cosby. A chinless, linguistically-challenged simpleton who always spoke in virtual Ubbi Dubbi, tantamount to an overdose of novocaine in the mouth, according to Cosby's "Dentist" monologues. Mushmouth plays a homemade bass guitar in the Junkyard Band.

Dumb Donald ? Voiced by Lou Scheimer. A lanky but dimwitted fellow; he always wears a green long-sleeved jersey three sizes too big, and a pink stocking cap covering his entire face except his eyes and mouth. In the Junkyard Band, Dumb Donald plays a trombone made out of plumbers' pipe and a morning glory horn from an old Victrola.

Bill ? Voiced by Bill Cosby. A character based on Bill Cosby. Like the others, Bill is an all-around good athlete, but more often he spends his time trying, though not always successfully, to keep his little brother Russell out of trouble. In the Junkyard Band Bill plays homemade drums made from a discarded foot-pedal trash can using spoons for sticks.

Russell ? Voiced by Jan Crawford. Bill's little brother (named after Cosby's real-life brother, whom he often talked about in his monologues) and the smallest and youngest of the Junkyard Gang. He always wears a heavy jacket, boots and winter hat regardless of the weather. Russell is a frequent antagonist and has a penchant for telling things like they are, much to his older brother's consternation. Russell plays the xylophone in the Junkyard Band (made out of empty cans and a discarded coat rack)

Weird Harold ? Voiced by Gerald Edwards. A tall, skinny, beady-eyed kid who always wears a yellowish-brown dress blazer, a brown sock on one foot and a red sock on the other. Fat Albert's best friend, Harold is usually clumsy, except on the basketball court. In the Junkyard Band Weird Harold plays a harp made from bedsprings, and on occasion plays a "dressmaker dummy" in the percussion section.

Rudy Davis ? Voiced by Eric Suter. A sharply-dressed smooth-talker and huckster whose smart-alecky attitude is always getting him into trouble more often than out of it. But to his credit, Rudy has a good heart and often learns his lesson. His family is implied to be financially better-off than the others as he is the only Junkyard Band member with a real musical instrument, an electric guitar.

Bucky ? Voiced by Jan Crawford. As his name indicates, Bucky has a large overbite. Bucky plays a stovepipe organ in the Junkyard Band.

Recurring characters

Mrs. Bryfogel ? The kids' first teacher and mentor, a matronly black woman. In the "Brown Hornet" and "Legal Eagle" years, the kids went to a different school where their teacher and mentor was Miss Wucher, a blond Caucasian. (Interestingly enough, both characters were voiced by the same actress, Jay Scheimer, wife of executive producer Lou Scheimer)

Mudfoot Brown ? An old sage and unemployed vagrant who gives advice to the gang, often using reverse psychology to get his point across. (Also voiced by Bill Cosby.)

The Brown Hornet ? A Show-within-a-show about an African-American superhero (a parody of The Green Hornet), whose cartoons were watched regularly by the gang.

Stinger ? The Brown Hornet's beefy sidekick whose gruff exterior masks a soft heart.

Computer (a.k.a. Tweeterbell) ? A female robot assistant to The Brown Hornet and Stinger.

Legal Eagle ? Another show-within-a-show, involving a crime-fighting cartoon bird and two lazy squirrel underlings.

Margene ? A white classmate and good friend of Fat Albert's. In one episode she and Albert ran for co-president of the Student Council and beat out two other candidates, both of whom were running on platforms of racism (one was black, the other Caucasian). A straight-A student, Margene occasionally got in with the wrong people but always managed to rebound; in another episode she got hooked on drugs, and yet another she got innocently involved in a violent white supremacy cult.