Margaret McPoyle is a member of the McPoyle family.
- Margaret is a deaf-mute. ("Charlie Goes America All Over Everybody's Ass"), ("The Gang Gets Held Hostage")
- She's in an incestuous relationship with her two brothers. ("Charlie Goes America All Over Everybody's Ass")
- She mimics the action of anyone nearby. ("The Gang Gets Held Hostage")
- She was seen kissing Dennis in Paddy's bathroom. ("The Gang Gets Held Hostage")
- She had sex with Mac at the Halloween party in Paddy's bathroom. ("Who Got Dee Pregnant?")
- During Margaret's first appearance, Liam said to Dennis "She's mute, dude". Also, earlier in the same episode we saw how Liam was actually talking to her. ("Charlie Goes America All Over Everybody's Ass") But in 03x04 Liam insists that she's a deaf-mute.
- Ep. "The Gang Gets Invincible" has a production code IP03010 - i.e. it should go AFTER "The Gang Gets Held Hostage" (IP03009). Here is why Charlie said about Margaret in 03x02 "Oh, good to see her AGAIN. Good. She doesn't know what I'm saying, right?" - if you follow the official chronology of the series, you'd notice what before this episode Charlie had seen her only once, in 02x09, and then he immediately got fork-stabbed. Plus, Dennis and Mac were convinced what Margaret is JUST MUTE.
- Despite the fact that she's deaf-mute, Liam was yelling at Mac "YOU WILL CALL HER!!".
("Who Got Dee Pregnant?")
- A deaf-mute Margaret was playing the cello on Liam's wedding. ("The Maureen Ponderosa Wedding Massacre")
- Ep. "McPoyle vs. Ponderosa: The Trial of the Century", The Lawyer asks Margaret to show a picture of mother to the court, which she does immediately, despite being deaf.