(Note: This only refers to episodes of sagas I have seen so far. If I am ever able to see the different Piccolo sagas of "Dragon Ball," as well as episodes of the Red Ribbon Army Saga / General Blue Saga that I haven't gotten to see yet, this list may change later.)
5. Emperor Pilaf, he's SO funny and SO stupid!! 
4. Tie: General White/Colonel Violet (even if she wasn't THAT major of a villain, she's STILL smoking hot!) 
3. Ninja Murasaki.
2. Tien Shinhan (before he turned good and even when he became good.) 
1. Mercenary Tao, he killed Bora AND nearly killed Goku! 