Karen

Karen appears in three episodes. First in a cameo in The End, as a customer in line. In The Laziest, it turns out that she and Larry were going to marry before Larry freaked out and threw food at her, causing them to break-up. She reappears in The Goons, where she's seen having a picnic with Larry as he proposes to her again, implying they may have gotten back together.

Trivia

 * The receptionist in "The Painting" looks exactly the same as Karen, except she's yellow instead of pink.