The character of Ranma and the initial inspiration for the entire series originally spawned from Ryuunosuke Fujinami, a secondary character in Rumiko Takahashi's previous work "Urusei Yatsura" (1981). Ryuunosuke is a girl raised by her maniacal, single father to be a boy, and became skilled in martial arts through his daily, brutal training. She constantly longs to express her pent-up feminine side, but obstacles (usually her father) keep getting in her way.
Rumiko Takahashi was originally going to have the characters "change" whenever they were hit or punched, but changed it to hot/cold water when she realized the characters would change every few seconds during a fight scene.
This anime was actually canceled on September 16, 1989 due to low ratings. One month later, the series was relaunched as "Ranma 1/2 Nettohen".
Manga creator Rumiko Takahashi derived Ranma's name from the Japanese expression "kaitô ranma" which means "solving a problem swiftly and skillfully". She based it from that phrase because she was having difficulty thinking up a name for him.
Due to the negative backlash towards the English dub, Brigitta Dau was fired after playing the voice of female Ranma for the first six episodes of the TV series and the first two episodes of the OAV series. Since then, Venus Terzo has taken that role, resulting in a much improved English dub.