Note the year, pilgrims.
CBS had first commissioned a pilot for Mr. Terrific in the spring of 1966, clearly inspired and influenced by the success ABC was enjoying with Batman. However, as we already know, the network then ordered a 2nd pilot, with a completely new cast.
Alan Young, fresh from Mister Ed, was cast as Stanley Beamish. Edward Andrews, who had starred on ABC's Broadside, was his government contact. Veteran actor Jesse White, for years the Maytag repairman in commercials, played Stanley's boss. In this version, Beamish is a bumbling shoe salesman in a department store.
Obviously, the network figured they needed a younger actor to be the lead, hence scrapping this pilot in favor of a 2nd, headlined by a relative unknown, Stephen Strimpell. Although Young still had a flair for physical comedy, time was not on his side.