- Judy Garland as Dorothy Gale
- Frank Morgan as Professor Marvel and the Wizard of Oz, the Gatekeeper, the Carriage Driver, and the Guard at the Wizard's door
- Ray Bolger as "Hunk", a farmhand, and the Scarecrow
- Bert Lahr as "Zeke", a farmhand, and the Cowardly Lion
- Jack Haley as "Hickory", a farmhand, and the Tin Man
- Billie Burke as Glinda, the Good Witch of the North
- Margaret Hamilton as Almira Gulch and the Wicked Witch of the West
- Charley Grapewin as Uncle Henry
- Pat Walshe as Nikko
- Clara Blandick as Aunt Em
- Terry as Toto
- The Singer Midgets as The Munchkins (See Munchkin § Actors and actresses)
Uncredited
- Mitchell Lewis as the Winkie Guard Captain[15]
- Adriana Caselotti as the voice of Juliet in the Tin Man's song "If I Only Had a Heart"[16]
- Candy Candido as the voice of the angry apple tree[17]