The Rat is the climax's antagonist of Lady and the Tramp. The rat also made numerous appearances in several other productions outside the original film.
Lady first encounters the rat while she is running happily in the backyard. She sees the rat, growls, and chases after it, causing the rodent to scatter through a hole in the fence. The rat has a bigger antagonistic role in the climax of the film, when it comes back to Jim Dear and Darling's house through the fence hole while Lady is tied to her doghouse on a rainy night. While Lady barks at the rat, Aunt Sarah tells her to shush. Tramp hears Lady's barks, and she tells him that the rat is in the house. Tramp follows the rat to the baby's room just in time before it can harm the baby. The two engage in a fight, until at one point, the rat gets to the top of the baby's crib, about to kill the baby. Tramp chases the rat off the crib, while overturning it by accident, causing the infant to cry. Finally, Tramp manages to corner the rat behind the couch and kill it.
Having been alerted by the commotion, Aunt Sarah arrives and, not seeing the rat, mistakenly believes that Lady and Tramp had attempted to harm the baby, promptly locking Lady in the basement and sending Tramp off to the pound. However, as soon as Jim Dear and Darling return, Lady shows them the body of the rat, clearing Tramp's name.
- In an early script, the Rat's name was Herman.
- The Rat is the only Lady and the Tramp antagonist that doesn't make any sound whatsoever other than a few squeaks, while it was being attacked by Tramp.
- It is never outright stated that the Rat wants to harm the baby. However, it is implied as it sneaks into the baby's room, and, at one point, jumps onto the baby's crib, but is thrown off by Tramp.
- The Rat, Si and Am, and the Stray Dogs were the only Disney Villains in Lady and the Tramp who didn't have redemption.
- The Rat was the only villain to die at the end.
- The Rat's gender is unclear, perhaps male since he was named Herman in the early script.
- The Rat was animated by Wolfgang Reitherman, who also animated Monstro, the climax's antagonist of Pinocchio.
- The Rat's breed might be a Brown Rat.
Characters: Lady | Tramp | Jock | Trusty | Aunt Sarah | Si and Am | Jim Dear | Darling | Jim Jr. | Tony | Joe | Policeman | Professor | The Dogcatcher | Stray Dogs | Al the Alligator | Hyena | Mr. Busy | The Rat | Peg | Bull | Toughy | Boris | Pedro | Dachsie | Scamp | Angel | Annette, Danielle and Collette | Buster | Reggie | Francois | Sparky | Mooch | Ruby | Scratchy
Songs: Bella Notte | Jock's Song | What is a Baby? | La La Lu | The Siamese Cat Song | He's a Tramp | Welcome Home | World Without Fences | Junkyard Society Rag | I Didn't Know That I Could Feel This Way | Always There