Ranma Saotome: The protagonist and a genius martial artist who turns into a girl with cold water and a boy with hot water. He is in an arranged engagement with Akane Tendo.

Genma Saotome: Ranma's father. He carries a curse that turns him into a panda when splashed with cold water and possesses an irresponsible and shameless personality.

Soun Tendo: Akane's father and Genma's old friend. He is the head of the dojo who often displays exaggerated emotions through tears.

Ryoga Hibiki (P-chan): Ranma's eternal rival who suffers from a directionally challenged condition so severe it's pathological. He turns into a cute black piglet (P-chan) with cold water and harbors a secret crush on Akane.

Shampoo: A girl from the Chinese Amazon tribe. After Ranma defeated her in his male form, she pursued him to make him her husband. She turns into a cat with cold water (a natural enemy to Ranma, who is deathly afraid of cats).

Ukyo Kuonji: Ranma's childhood friend and a candidate for his fiancée who runs an okonomiyaki shop. She dresses as a boy and uses a giant spatula as a weapon.

Nabiki Tendo: The cunning and money-hungry second daughter of the Tendo family.

Kasumi Tendo: The gentle and calm eldest daughter of the Tendo family who handles all the household chores.

Tatewaki Kuno: The captain of the kendo club who is in love with Akane and simultaneously infatuated with Ranma's female form (the 'pigtailed girl').

Mousse: One of Ranma Saotome's primary rivals, a member of the Chinese Amazon tribe with a pure, unrequited love for Shampoo. His name comes from hair mousse, and he is Shampoo's childhood friend. He is extremely nearsighted and turns into a duck when touched by cold water.