The wife of Son Goku in Dragonball Z. Her father is the Ox King, a powerful fighter who terrorized people for many years, finally stopping shortly after meeting Goku for the first time. Chi Chi met Goku when they were around 12 or so. She is a tough woman, evidenced by the fact that Goku is either off fighting someone or another in space, or is dead, for a significant portion of the time they are married, and yet seems able to go on with a daily routine with very little fuss and bother. She is the mother of Gohan and Goten.
Chi Chi herself is an excellent fighter, and in fact, Goku and Chi Chi fought each other in the World Martial Arts Tournament on the day of their wedding.
Chi Chi also apparently means (or at least is some kind of slang for) "breasts" in Japanese, and some jokes are made in this direction early on in Dragonball, mostly by Master Roschi.