| O A e o Z | |
| Type: | studio |
| Artist: | Os Mutantes |
| Cover: | O A e o Z.jpeg |
| Released: | 1992 |
| Recorded: | 1973 in Estúdio Eldorado, São Paulo |
| Genre: | Progressive rock, psychedelic rock |
| Length: | 48:16 |
| Label: | Polydor |
| Producer: | Peninha Schmidt, Allan Watts, Os Mutantes |
| Prev Title: | Tudo Foi Feito Pelo Sol |
| Prev Year: | 1974 |
| Next Title: | Tecnicolor |
| Next Year: | 2000 |
O A e o Z (also known as A e o Z, or "A" e o "Z", Portuguese: The A and the Z) is an album by Brazilian rock band Os Mutantes. It was their first record without founding member Rita Lee, and marked a shift in their sound to progressive rock. Recorded in 1973, but shelved until 1992, this was Arnaldo Baptista's last studio record with the group.