"Nancy" (left) with Maxwell Smart.
Codename from a "little black book" left in Maxwell Smart's apartment by KAOS defector Gina Matusik.
When Max's visiting Army buddy Sid Krimm finds the book he thinks it is Max's address book and calls "Nancy" for a date. The number rings at the lair of KAOS assassin The Maestro who orders one of his henchwomen to go posing as Nancy while the Maestro searches Max's apartment for the book.
This otherwise unnamed henchwoman is portrayed by Ann Prentiss [Episodes #76 & 77: "The Little Black Book, Parts 1 & 2"].