Rollo

 is one of Samantha's old boyfriends. Her rejection of him is the only "blot on his record".

Endora persuades him to try to win her back from Darrin by giving her a love potion. The plan backfires when Endora accidently drinks it and falls in love with Darrin's client, Bo Callahan. It is up to Rollo and Samantha to stop Endora from marrying Mr. Callahan before midnight when the potion wears off.