Karvelas was born in New York City with a twin brother and grew up in Charleroi, Pennsylvania.

Karvelas was a Golden Gloves boxing champion while serving in the United States Marines during World War II and later worked as a stockbroker.

Wanting his cousin to remain close to him, Adams initially gave Karvelas several uncredited bit parts on Get Smart.

In Episode 21, Season 5, Smart tells the Chief, "People ask if Larabee and I are related."

Robert's character part, and his generally sweet, unassuming nature, enhanced the joviality of Get Smart.