Dragon Ball Z (or Dragon Ball Z Budokai Tenkaichi) is the sequel to the anime Dragon Ball. Goku, Gohan (his son) and the Z fighters help save the world from Raditz and others numerous times in Dragon Ball Z episodes. The saga continued as Dragon Ball GT.
these series ended on there terms, some of these finales were epic and will forever go down in tv history as amazing. and some were absolutely trash (cough, castle, cough, cough). but all in all they got to run there course which is all any writer/tv fan wants closure