Majin Buu
    Majin Buu was the last main villan that the Z warriors had to encounter and the beast definitely gave the warriors a run for their money.  Majin Buu was created by the great Babidi's father, Bibidi, but later was sealed away by the grand kais.  Eventually Babidi and his servent, Dorbua, were able to release Buu from his seal using the energy from Goku and Majin Vegeta.
     Buu appears in numerous forms.  First as Fat Buu.  Later Fat Buu is turned good by Mr. Satan.  But a gun shot that injured Satan's dog pissed Buu off to the point of releasing another Buu inside of Buu.  The good and evil Buus fought but the evil Buu was too strong and ate the fat Buu as a cookie.  This turned Buu into Super Buu who faught against Gotenks and Piccolo, but later absorbed Gotenks to become super mega Buu and so on.
     Buu is the most powerful villan ever.  No one could beat him.  Goku turned SS3 but still couldn't handle him.  Vegeta died trying to self destruct near Buu, but Buu survived.  It took the might of Veggito to finally make Buu lose momentum and then a Genki Dama from Goku to finally put an end to Buu's terror.  Buu was the first villan that was able to destroy the Earth.  The battle was long and seemed endless, but the Z warriors prevailed.