A younger version of Rizzo the Rat is seen in Disney Junior's Muppet Babies. He first appeared in the episode "How Kermit Got His Groove," where it's revealed he lived behind a hole in the wall. Making a mess in the playroom, he informs the babies that he's decided to move in, challenging Baby Kermit to a dance-off to determine whose playroom it is. After Kermit wins the dance-off, Rizzo sadly admits defeat and plans to leave them alone, but Kermit informs him that he's welcome to come over and play anytime.
Rizzo goes on to become a recurring guest character in the show. He makes a cameo in a fantasy sequence in "Summer Penguin P.I," he appears as the "picky" customer in Kermit and Fozzie's pizza parlor in "Best Pals Pizza Parlor Palace," he plays the Tooth Fairy in "Tooth and Consequences," he joins the gang in trying to stop a giant Animal in "Animal Kong," and he pretends to be a puppy so the other kids can practice taking care of one in "Puppy for a Day." He continues to make sporadic appearances into the second season, including "Meatball Mayhem," where, for the first time, he turns down the offer of free food.
The 2018 series is Rizzo's first on-screen appearance with the Muppet Babies, but he'd been referenced in merchandise in relation to prior versions of the franchise. A 1986 Colorforms set notably includes characters not seen on the animated series including Gaffer, a more chicken-like Camilla, and Rizzo. Having been established in illustrated form, a baby rat appears four years later in Muppet Babies' Classic Nursery Rhymes and Muppet Babies' Classic Children's Tales as an established fixture in each photo pictorial in both books and illustrated by Tom Brannon in the accompanying text.
Rizzo's siblings are named in the third season premiere episode: "There's Markie, Mikey, Danny, Davey, Vinny, Timmy, Tammy, Tommy, Robbie, Ronnie, Johnny, Jennie, and Craig." His brother Ricky (voiced by Jessica DiCicco) can briefly be glimpsed in "Summer's Car Trouble".
- Disney Muppet Babies (2018)
- Episode 105: How Kermit Got His Groove
- Episode 107: Summer Penguin P.I. (silent cameo)
- Episode 109: Best Pals Pizza Parlor Palace
- Episode 111: Upside Down Day (brief cameo)
- Episode 111: Tooth and Consequences
- Episode 112: Animal Kong
- Episode 116: The Card Shark
- Episode 120: Puppy for a Day
- Episode 120: No Laughing Matter
- Episode 203: Finders Keepers
- Episode 206: Mystery on the Muppet Express (silent cameo)
- Episode 208: My Brother Vinny
- Episode 209: When You Wish Upon a Rizzo
- Episode 211: Wocka by Fozzie
- Episode 212: Meatball Mayhem
- Episode 216: The Spoon in the Stone
- Episode 219: Secret Agent Double-Oh-Frog (silent cameo)
- Episode 220: Rise of the Pickler (brief cameo)
- Episode 221: Block Busters
- Episode 301: Oh Brother
- Episode 310: Animal and the Little Accident
- Episode 312: Best Pals Pizza Delivery (brief cameo)
- Episode 314: Dueling Harmonicas
- Episode 315: Best in Chicken Show
- Episode 315: No Takesies Backsies (brief cameo)
- Episode 319: Gonzo-rella
- Episode 319: Summer's Car Trouble
- Episode 322: Rizzo for Mayor