In the American TV sitcom "Bewitched", what was the name of Samantha's identical cousin?

"Bewitched" is an American television sitcom fantasy series, originally broadcast for eight seasons on ABC from September 17, 1964, to March 25, 1972. It is about a witch who marries an ordinary mortal man and vows to lead the life of a typical suburban housewife. The show enjoyed great popularity, finishing as the number two-rated show in America during its debut season, staying in the top ten for its first three seasons, and just missing this mark with an eleventh place ranking for both seasons four and five.

Serena (Elizabeth Montgomery) is Samantha's cousin. Serena is egocentric and looks like Samantha (except for a tattoo under her left eye). Also played by Montgomery, Serena is credited as "Pandora Spocks" (a spin on the phrase "Pandora's box") in many of her appearances from 1969 to 1971. Serena is first seen in episode, #54, "And Then There Were Three".

Serena is the antithesis of Samantha, in most episodes sporting a beauty mark on her cheek, (the beauty mark changes from one episode to another, often referencing the theme of the episode) raven-black cropped hair and mod mini-skirts. Ever mischievous, bawdy and irresponsible, Serena often flirts with Larry Tate (calling the white-haired Tate "Cotton-Top"), just for sport. She occasionally dates mortals and has been known to flirt with Darrin, while pretending to be Samantha.