Honorable mentions include Raditz, who is responsible for Goku dying, Piccolo Jr., who actually killed Goku, but was never really a villain imo (he just thought he was, similar to Tien), Nappa, and the Ginyu Force, especially Recoome. Majin Buu is also a fav of mine, but he's the child emperor shooting his BB gun at peasants; he isn't amazingly responsible for his actions until he becomes Super Buu, and Super Buu is... not a good character, much less a good villain.
Nothing filler is on this list btw, because they all suck, except Mystical Adventure, which just rehashes the Red Ribbon Army.
Zarbon is also not on this list, Repeat, Zarbon is NOT on this list (although look at those eyes)
Dr. Gero
I considered putting 17 and 18 on this list together, but they're even less villainous than Piccolo and Tien, and their actually evil future counterparts are decidedly different characters, with a past only referenced and feats we aren't privy to outside of the non-canonical History of Trunks.
Even if 17 and 18 had been the real villains of the Android Saga, this dude's shadow would still loom large over two huge sagas -- being directly responsible for Eighter and all the other androids. Maybe he even designed those doubledecker tanks the RR Army loved so much??
One of the things I adore about Dragon Ball is how Toriyama doesn't usually design his villains to be traditionally Cooooool. Sure, sometimes he provides, but you'll mostly get a small gremlin, short hitler, assassin in pink, fat pink bubble gum monster, short despot, another short despot, girl and boy twink, fat clown, and, in this case, an old man in baggy pants. However, unless the character is just for gags like Pilaf, he still makes these nonconventional villains just as baller as your Sephiroths, Madaras, etc., and Dr. Gero is no exception.
So what if he's an old bald man in baggy pants? He fucks. He canonically fucks even (looking at you 16). He fists yamcha. Destroys city. He murders the fuck outta that car dude and sets an ominous tone that carries over into the Cell portion of the saga.
I like him
Beerus
The only character from Super on this list and that's because Super sucks (GT is an actual abomination though, so don't expect a bait and switch Super 17). However, Battle of the Gods is a great movie, and Beerus is an even better character. He's also (usually) not an antagonist, but he's certainly a villain. I think Buu or maybe Frieza maaaaay have a bigger body count, although the only reason would be Beerus' consummate laziness.
King Piccolo
First and only villain to make a wish, murderer of Roshi (effectively), Chiaotzu, and Shenron, and responsible for the death of Krillin and Goku's first nimbus. He also figures nicely into the backstory of Roshi and the history of the Dragon Ball world.
Him sleeping with his eyes open is neat too
The only reason he's not higher on this list is due to the myriad retcons that surround him and the Namekians. For instance, Dragon Balls seem mythic at first, but they're actually less than 300 years old. If Kami is significantly stronger than him, why was he content to let King Piccolo do world genocide TWICE? Why not send Popo if he can't? (him being a Namekian and Kami's other half is a good retcon tho, it's just clunky).
Frieza
I stan a short king
Vegeta
I don't think Geets has the first beam struggle, but he has the best (objective), with the stakes being the fate of the world. He also has the best fight in the series (objective), with his arc killing half of Dragon Team's fighters, and his fight requiring the other half. And it's still a nail biter!
I stan a short prince
Tao Pai Pai
This fucker has so much swagger. Dude kills General Blue with his tongue, wears a pink chang pao that says 'Kill You', rides around on various shit he throws, and gets an evil nimbus in the filler. Oh yeah, and he absolutely obliterates Goku in their first fight. The only people Goku even struggled with before this was Yamcha, who beat a hungry hungry Goku, General Blue, and Jackie Chun, and none of them came close to outclassing Goku the way Tao did. He also never overstayed his welcome; every scene with him is dope af
