In each of his first three seasons, Donovan played for a team which went out of business. He started out with the first Baltimore Colts, who folded after his rookie season in 1950, followed by the New York Yanks in 1951, and their successor, the Dallas Texans, in 1952. After the Texans franchise was moved to Baltimore in 1953 and became the second Baltimore Colts, Donovan played with that team. He became one of the stars in an outstanding defense and was selected to five straight Pro Bowls, from 1953 through 1957. The Colts won back-to-back championships in 1958 and 1959. He was selected to the Pro Football Hall of Fame in 1968.

This Baltimore Colts mini helmet was signed in blue by Donovan and inscribed, "HOF '68." This mini helmet includes a BCO hologram.