Irvine is Oscar's niece, a baby Grouch. She stayed in Oscar's trash can while he was away, in episode 2606 of Sesame Street. She has also made many other appearances on the show, up through Season 30. She has a tendency to scream and cry very often. Her parents are not seen in the series.
In Episode 2402, Maria watches Irvine while she's taking her nap for Oscar, who has to go the Grouch supermarket. Unfortunately for Maria, the Count wakes Irvine up with his counting, and Maria can't get Irvine back to sleep. Biff and Sully (mainly Biff) read her the story of Cinderella, but that doesn't work either. The Two-Headed Monster plays her a violin lullaby, but that doesn't work and they start crying too. When Oscar returns, he tells Maria that there's only one way to get a Grouch baby to go back to sleep. He starts an argument with Grundgetta, which immediately put Irvine back to sleep. Oscar says Grouch babies love to fall asleep to the sound of a good loud argument. They continue arguing whie an exasperated Maria announces the sponsors. In a 1998 episode, Irvine insists that she be allowed to take a bath, much to the concern of Oscar. After allowing Irvine to take a bath, Oscar remarks, "She may be clean, but she's still ugly."