Asparagus (Gus)
Asparagus, also known as Gus, is a very old tomcat. He is light brown and his "coat is shabby". His paws shake because he has palsy. He once was a great actor ("when Victoria reigned", which shows his great age, if we assume CATS is set in the 20s), but he is old and weak now. He is very close to Jellylorum, so she might be his daughter or another relation.

In the film version is another cat, named Asparagus jr.

 frail, wise, historied

Bustopher Jones
Bustopher Jones is the cat about town. He wears white spats and a monocle and always carries a red rose. He is very large, thanks to his passion for lots of good food. He is also very charming, as all the older queens fall for him.

 foppish, gluttonous, dapper

Grizabella
Grizabella is the protagonist of CATS. She once was beautiful and loved, but she left the Jellicles to live a more exciting life. Once a "Glamour Cat", she came back as a shabby old queen who has lost all her of beauty, her friends and her happiness. 

 proud, hurt, indomitable

Growltiger
Growltiger was one of Gus' greatest roles. He only appeared in "Growltiger's Last Stand". He was a pirate.

Jennyanydots
The old Gumbie Cat has an orange fur with tiger stripes and leopard spots. She sleeps all the day, but at night, she's awake and teaches the mouses and beatles to be behave and to dance or crochet. She might be the mate of Skimbleshanks.

 motherly, controlling, contended

Macavity
Macavity's a mystery cat, so Demeter says. He's a criminal, also called the Napoleon of Crime. He is red, orange, black, white and yellow and has a large mane. He trapped and kidnapped Old Deueronomy.

 hypnotic, jealous, dangerous

Mister Mistoffelees/Quaxo
Mister Mistoffelees is the magician of the Jellicles. He's black with a white chest and a white face. He's very small and very quiet. He hides his magical powers in the first act and is called "Quaxo" then. He is the one who brings Old Deuteronomy back, using magic.

 competitive, neat, electric

Mungojerrie and Rumpelteazer
Mungojerrie is the male part of the famous double "Mungojerrie and Rumpelteazer", two cheeky kittens. He is orange with black stripes. He's the brother or the mate of Rumpelteazer, who is the female part of the duo and looks a little bit like a female version of Mungojerrie. One may consider them to be criminals - or simply cheeky young kittens.

 mischievous, rambunctious, ne'er-do-well

Old Deuteronomy
Old Deuteronomy is the leader of the Jellicles. He is a very old tomcat with a thick brown coat. He was kidnapped by Macavity in the second act, but brought back my Mr Mistoffelees in the next song. He is commonly assumed to be the father of Munkustrap, the Rum Tum Tugger and probably even Macavity. Old Deuteronomy is well loved by the whole tribe.

 wise, commanding, spiritual

Rum Tum Tugger
The Rum Tum Tugger is a handsome rebel, well loved my most queen cats, especially Bombalurina and Etcetera. He appears to be close to Munkustrap and Old Deuteronomy and is probably their brother and son, respectively. The Rum Tum Tugger does not appear to like Grizabella at first, but warmly welcomed her back in the end, like all the others.

 vain, perverse, inconsequent

Skimbleshanks
The Railway Cat! He's the one, who organises everything on the railway and he doesn't like disorderly behavior. He is might be the mate of Jennyanydots.

 caring, bright, self-regarding // punctual, proud, energetic