Dogs:
* Lady: A beautiful, purebred Cocker Spaniel who is pampered and loved by her owners.
* Tramp: A streetwise, scruffy mutt who is initially suspicious of humans but gradually warms up to Lady.
* Trusty: A wise and loyal Bloodhound who is Lady's best friend.
* Jock: A cocky and energetic Scottish Terrier who is Lady's other friend.
* Buster: A grumpy and territorial Bull Terrier who is Jock's friend.
* Peg: A sweet and sassy Pekingese who befriends Lady while she is on her own.
* Bull: A tough and demanding Bulldog who is Peg's boyfriend.
* Siamese Cats: Two mischievous Siamese cats who are a constant source of trouble for Lady.
Humans:
* Jim Dear: Lady's loving owner.
* Darling: Lady's loving owner.
* Aunt Sarah: Jim Dear and Darling's aunt who comes to visit and brings her annoying, spoiled little terrier, "the baby."
* The Delivery Man: A friendly man who delivers the baby.
Other Animals:
* Boris: A grumpy, old tomcat who lives with Peg and Bull.
* The Rat: A large rat that Tramp fights in the alley.
* The Horse: The horse that pulls the wagon during the spaghetti scene.
This list includes the major characters, but there are also several minor characters that appear throughout the film.