Penelope Chase was a character from the adventures of Herbert "Daring" Dashwood.
She is mentioned in a file on Herbert's computer, in which Dashwood only says "Two-timing bitch. She got what she deserved." If the broadcast is taken to be true, then she was the "Black Widow", the leader of the slavers of Paradise Falls at the time, followed by Harmon Jurley. She tricked Dashwood into taking her into Rockopolis in order to enslave the populace. Upon discovering her true identity, Argyle ripped out her heart with his "Eagle Claw" attack. Rockopolis was destroyed and Argyle was killed in the ensuing battle with the slavers.
Penelope Chase is mentioned in Fallout 3, but does not actually appear.