Sonja may refer to:
1. KAOS agent who works at Knight's Stamp Redemption Centre, actually a front for KAOS's munitions depot.
Portrayed by Nancy Kovack [Episode #102: "The Day They Raided the Knights"].
2. KAOS agent, a 99 lookalike, who takes 99's place as part of a plot to poison 99's husband Maxwell Smart and frame the real 99 for his murder. See also League of Impostors.
Portrayed by Barbara Feldon with voice by June Foray (uncredited) [Episode #133: "And Only Two Ninety-Nine"].