Super No. 17
From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
 Early conception
After the evil Baby is killed by Son Goku, peace was thought to have been finally restored. However, in the depths of Hell, two masterminds worked on a horrific plot. Doctor Gero, the evil brilliant scientist who was responsible for all of the Artificial Humans, and Mu, who was responsible for the completion of Baby, teamed up to create the ultimate being. They decided that by merging No. 17 with a Machine Mutant that they created in Hell they could create the ultimate killing machine.
Mu and Doctor Gero then used the Machine Mutant clone to brainwash No. 17 into joining them and using both No. 17s to sync their energies together to open the gates of Hell, allowing themselves and mostly all other previously defeated villains to escape. No. 17 then asked his twin sister, Artificial Human No. 18, to join them, but would wind up killing Krillin when he tried to contradict Hell Fighter 17's voice in No. 17's head and later fending off No. 18's attack with relative ease. A short time later, No. 17 reached his Hell Fighter counterpart, interrupting the latter's fight with Vegeta, at the same time as the Z Warriors.
 Fusion and defeat
At this point, the two No. 17s finally fused together and transformed into the penultimate killing machine, Super No. 17. Super No. 17 then battled Vegeta, Son Gohan, Son Goten, Trunks, and Majuub (Goku was trapped in Hell) and defeated them all. He also once again killed Doctor Gero and Mu revealed that he had programmed Super 17 so that he would have full control, leaving none for Doctor Gero.
Goku then returned to Earth with some help from Piccolo and Dende. He immediately engaged Super 17 and, once transformed into a Super Saiyan 4, was able to fight competently against him. However, Super 17 was able to absorb all of the energy attacks that Goku unleashed on him and by the time Goku realized this, Super 17 has absorbed enough energy to overwhelm the Saiyan. At that point, he is stonger than Goku and could hold his own against Baby.
No. 18 came to Goku's aid and distracted Super 17 long enough for Goku to find his weak spot. Eventually, Goku noticed that while Super 17 was in his Absorption pose, he had created a shield around him to prevent No. 18's blasts from reaching him, all the while laughing hysterically. It was at that point that Goku realized Super 17's sole true weakness. When Super 17 absorbed energy, he was actually vulnerable to attack. Goku charged Super 17 with the Dragon Fist, blowing a hole straight through him. He then shot a barrage of Kamehame-Ha that finally killed the Super 17 once and for all. It was later explained that No. 17 had been influencing Super 17 to reveal this weakness in order to make himself vulnerable to attack.
- Absorption Barrier – Like No. 19 and No. 20, Super 17 has the ability to absorb energy into himself through a certain pose and add it to his own. This is a feature Mu installed into Super 17 without Dr. Gero's knowledge. He has made this his own type of Absorption ability by not only regaining energy by stealing it, but by adding it to his maximum power and making him stronger. He doesn't absorb energy with the inlet devices on his hands (or rather, in his case, on his gloves) like the other two, instead he extend his arms and legs outward to somewhat resemble a star and raise an invisible field capable of absorbing what seems like anything as long as he holds that pose. The limit on how much energy can be absorbed (if there is one) is unknown, as he even absorbed Goku's 10x Kamehameha. This unfortunately leaves him open for physical attacks, as he can not counter while absorbing energy.
- Android Barrier – No. 17's signature defense technique which has been retained in this super form. This is an Energy Shield that protects Super 17 from harm, and seems to be very resilient enough to withstand Goku's self destruction technique.
- Flash Bomb – Super 17 places both hands forward with his fingers stretching out, concentrating energy into his fingertips. He then fires several hundred small yellow shots of energy that act as a machine gun blast. He also seems to be able to fire the attack in a cone shape, causing a shotgun effect.
- Super Flash Bomb – This is an enhanced version of Flash Bomb, as it has a longer range, being able to span across half the planet, and augmented power.
- Flight – Like most characters in the series, Super 17 can fly in the air. He flies by the means of a certain machine called Hikou in his body.
- Ki Blast – The most basic form of energy wave.
- Hell's Storm – This attack was only named in the Budokai Tenkaichi video game series, but it still holds enough danger to be counted as a named attack. Super 17 does what No. 16 does and takes off his hands, only one though, and instead of firing massive blasts from the gun hidden in his arm, he fires several hundred bullets much like Flash Bomb, only causing more damage by firing in a concentrated and narrow straight line. He used this move against Majoob.
- Shocking Death Ball (FUNimation dub: Electro Eclipse Bomb) – Super 17's most powerful attack. He places his hands forward as if he were going to do a flash bomb attack, only he forms a sphere of black energy that has another gray sphere inside it that turns black in the center and has red electricity flowing around it. If he charges the attack for a few seconds, it seems to take on a decagon shape, but most commonly looks like a circle. Once he fires it, it leaves a shot black trail of energy behind before it hits the target, very easily causing a small nuke sized explosion that destroys everything caught in the explosion. This is the attack he uses on Mu when he says to show no one controls him. An interesting point is that in the Budokai Tenkaichi series, the attack is called Shocking Death Ball, yet he calls out "Electric Hell Sphere".
- Thunder Eraser – An attack featured in Dragon Ball Z: Infinite World where dashes towards his enemy with an open hand and he sends purple energy outward to force his opponents backward and cause damage.
- Ultra Sensitivity – By concentrating his mind, Super 17 can sense the very changes in the air and sound, which allows him to detect even the stealthiest opponents, such as Goku using the Instant Transmission. This ability can be nullified with loud noises.
- Zanzo-ken – By moving at extremely high speeds, Super 17 can create after images that make the opponents think he is still standing on a certain location.
- According to the second GT Perfect File, the wish that Goku gave himself for at the end of Dragon Ball GT, which had brought back to life all the good people that died in the battles from the Super 17 Saga on through to the Shadow Dragon Saga, revived both Krillin and the real No. 17. This suggests No. 17's Fusion was not necessarily permanent, and what Goku said about Android 17 "holding back" Super 17 may have been true.
- In the Budokai Tenkaichi series, he is one of the the tallest non-giant characters (second only to Broly as a Legendary Super Saiyan).
- The way that Super 17 was defeated mirrored how Goku defeated Piccolo Daimao (specifically the part involving an animalistic powered fist through the chest).
- Super 17 is the shortest-lived villain to ever have a saga named after him; he was only in the series for seven episodes.
- Although he was a main antagonist of a saga, the only characters Super 17 ever killed were Doctor Gero and Mu, the two evil scientists who essentially created him. However, Hell Fighter 17 did indirectly cause the brainwashed original No. 17 to kill Krillin just before their merger.