Penny Pann is the secretary of Joel whom he has been having an affair with.
It is revealed in the Pilot that Joel has been having an affair with Penny Pann, his secretary, due to to not being happy in his marriage to Midge and also his work life.
When Joel's parents meet Penny they say she is not the type of girl you take to meet your parents.
Penny is described by Midge as being the "Methodist version of her" when she sees Penny and Joel living in an apartment together, which is almost identical to the apartment Midge and Joel lived in when they were together.
She seems to have a short temper as well, showing up and having an outburst at the make-up counter Midge worked at when she finds out Midge and Joel had slept together, making her a hypocrite since she had an affair with a married man.
Midge attempts to explain to Penny that she and Joel will not last as Midge and Joel have a much longer history.
Penny is a young secretary in her early twenties. She has dark brown hair and short bangs going across her forehead.