Karl Mayer was Susan's ex-husband, who left his wife and abandoned his daughter when he cheated with his secretary. A divorce attorney with an excellent reputation, and a sex drive just as well known, Karl eventually settled down and married a law professor, Marissa, and the pair had a son. However, the relationship didn't last and the two divorced. Later, Karl began a secret affair with his client, Bree Van de Kamp, as he tried to free her from her marriage to her husband. Karl died after being struck by a plane at a neighborhood Christmas party.