Diane Francis is Dr. Dave's old girlfriend from medical school. She only appeared in The Wedding Frame. At Dave and Lois’s wedding, Dave's mother hired Nikki LaPorte (actually Nicholas LaPorte) to play the role of Diane to ruin the wedding. But Noelle sabotaged Mrs. Dave's plan and exposed her treachery by bringing in the real Diane. She is voiced by Grey DeLisle.
At some point before the series Diane Francis and Dr. David Dave used to date, however they broke up and moved on. They meet again during The Wedding Frame when Noelle exposes Mrs. Dave's plot to break Dave and Lois apart.
She appears to be a kind woman. When she sees Dr. Dave at the wedding she greets him and says he hasn't changed a bit. This shows that they had something good when they were together and she still cares about him.
She wears a pink dress and a purple scarf when she arrives at the wedding. In her photo, she wears a red dress.
- She only appears in the final episode of the series.