Martha Sewer is a Grouch wedding planner and author who appears in a season 28 episode of Sesame Street. A take-off of Martha Stewart, she is described as "the perfect Grouch," as she does everything perfectly grouchy. She is also a Grouch wedding expert, having literally written the book on it (Martha Sewer's Book on Perfectly Rotten Weddings).
She arrives on the street following Oscar and Grundgetta's accidentally successful marriage proposal ("Rotten news travels fast," Oscar notes). The two Grouches are initially appalled at the idea of getting married, until they learn from Martha about the Grouchy party they can throw because of it and schedule the wedding for today (a perfect time for one; it's inconvenient for everyone).
She helps them make various preparations, including leaving a valuable wedding ring that Telly, the "ring loser," will have (and subsequently lose). When the wedding commences, Oscar and Grundgetta realizes they'd never enjoy married life and forgo the wedding, but decide to throw the party anyway. Martha attempts to collect the ring from Telly, who's finally lost it.