Bizarro appears in the October 1958 daily Superman comic strip by Alvin Schwartz and Curt Swan. Since the October issue of Superboy went on sale in August, it appeared first. However, which one was written first is unclear.
from Superboy (DC, 1949 series) #6 (January-February 1950)
in Superman Annual (DC, 1960 series) #2 (1960 [January 1961])
in Superman Annual (DC, 1960 series) #2 (1960 [January 1961])
in DC Special Blue Ribbon Digest (DC, 1980 series) #15 (November 1981)
in The Greatest Superman Stories Ever Told (DC, 1987 series) #[nn] ([November] 1987)
in The Greatest Superman Stories Ever Told (DC, 1989 series) #1 ([April] 1989)
in Superman Annual (DC, 1960 series) #2 (1960 [January 1961])
in DC Special Blue Ribbon Digest (DC, 1980 series) #15 (November 1981)
in The Greatest Superman Stories Ever Told (DC, 1987 series) #[nn] ([November] 1987)
in The Greatest Superman Stories Ever Told (DC, 1989 series) #1 ([April] 1989)First letters page.
in Superman Annual (DC, 1960 series) #2 (1960 [January 1961])
in DC Special Blue Ribbon Digest (DC, 1980 series) #15 (November 1981)
in The Greatest Superman Stories Ever Told (DC, 1987 series) #[nn] ([November] 1987)
in The Greatest Superman Stories Ever Told (DC, 1989 series) #1 ([April] 1989)