Gwendolyn "Gwen" Ling is Francine Smith's adoptive sister and a character from TV Series "American Dad!".
She was mentioned in the episodes "Meter Made" and "Big Trouble in Little Langley". However, she phisically appeared in the episode "Now and Gwen".
Gwen visits the family in "Now and Gwen". Hayley gets annoyed with her mom always covering for her and finally tells her off, receiving a vague warning. When she tells Francine, she discovers that Gwen took the blame for a school fire started when Francine tried to emulate her sister's smoking in school and had tried to make up for it ever since. As a result of Hayley's confrontation with Gwen, she plans on setting the school on fire and framing Francine for it. With Gwen admitting that she took the blame the first time due to her love for her sister, they work out their differences. Gwen offers Francine a cigarette to celebrate patching things up, but they set the school on fire and Francine agrees to take the blame and be arrested. But Gwen gets arrested for breaking her parole while Francine's charges are dismissed under a suspended sentence due to Stan's influence. As a result, Gwen promises revenge when she gets out. Meanwhile, Stan tries to teach Steve how to hug Gwen for a sexual thrill, but Steve proves to be an overachiever when Gwen mistakes him for being retarded and allows far more contact than Stan could dream of achieving.