The main cast members were called Mouseketeers, and they performed in a variety of musical and dance numbers, as well as some informational segments. The most popular of the Mouseketeers comprised the so-called Red Team, which consisted of the following:
Nancy Abbate (first year only)
Dennis Day (first and second year)
Cheryl Holdridge (joined in second year)
Cubby O'Brien ★
Karen Pendleton ★
Jay-Jay Solari (second year only)
★ Cubby and Karen were initially "Meeseketeers" because they were the youngest of this group.
The remaining Mouseketeers, consisting of the White or Blue Teams, were Don Agrati (later known as Don Grady when starring as "Robbie" on the long running sitcom My Three Sons), Sherry Alberoni, Billie Jean Beanblossom, Johnny Crawford, Jonathan A. Kahn (a.k.a. Tio Juan), Eileen Diamond, Dickie Dodd (not related to Jimmie Dodd), Mary Espinosa, Bonnie Lynn Fields, Judy Harriet, Linda Hughes, Dallas Johann, John Lee Johann, Bonni Lou Kern, Charlie Laney, Larry Larsen, Paul Petersen, Lynn Ready, Mickey Rooney Jr., Tim Rooney, Mary Lynn Sartori, Bronson Scott, Michael Smith, Margene Storey, Ronnie Steiner, Mark Sutherland and Don Underhill. Dennis Day was a Mouseketeer for two seasons; the others served for shorter periods. Larry Larsen, on only for the 1956–57 season, was the oldest Mouseketeer, being born in 1939. Among the thousands who auditioned but didn't make the cut were future vocalist/songwriter Paul Williams and future actress Candice Bergen.
Other notable non-Mouseketeer performers appeared in various dramatic segments:
Roberta Shore a.k.a. Jymme Shore
Steve Stevens (not to be confused with musician of same name)
Kevin Corcoran, a.k.a. Moochie
J. Pat O'Malley
Julius Sumner Miller as "Professor Wonderful"
These non-Mouseketeers primarily appeared in numerous original serials filmed for the series, only some of which have appeared in reruns. Certain Mouseketeers were also featured in some of the serials, particularly Annette Funicello and Darlene Gillespie.
Mickey Mouse Club was hosted by Jimmie Dodd, a songwriter and the Head Mouseketeer, who provided leadership both on and off screen. In addition to his other contributions, he often provided short segments encouraging young viewers to make the right moral choices. These little homilies became known as "Doddisms". Roy Williams, a staff artist at Disney, also appeared in the show as the Big Mooseketeer. Roy suggested the Mickey Mouse ears worn by the cast members, which he helped create, along with Chuck Keehne, Hal Adelquist, and Bill Walsh.