From Dragon Ball Encyclopedia, the ''Dragon Ball'' wiki
Yakon (ヤコン, Yakon; FUNimation "Yakon", Viz "Yakon") is a Darkian.
While his exact origins are unknown, Yakon's homeworld was referred to as Planet Darkness. He was a monster controlled by Babidi and portrayed as one of his strongest followers (and was possibly intended to be placed on Level 3 as Dabura claimed that sending Yakon to Level 2 was too drastic an action). He was a voracious monster with an apparently insatiable appetite, as seen when he greeted the Z Warriors and asked them which one he should eat first despite the fact that he had devoured two messengers Babidi had sent him only minutes before. His battle power was said to be 800 Kili (a unit of measurement that was different from the battle powers displayed on the conventional Scouters). As stated by Babidi, this was a level much weaker than Son Goku's battle power of 3,000 Kili (as a Super Saiyan). According to the Supreme Kai, he was one of the most feared creatures in the universe and was one of the most powerful beings in his quadrant of the universe. The Kaioshin refered to him as Majū Yakon (魔獣 ヤコン, Majū Yakon).
Dragon Ball Z
Yakon is first seen when Babidi sends two of his minions to fetch him so he can battle Son Goku, Vegeta, Son Gohan and East Kaioshin, but Yakon ate the minions that Babidi sent. Babidi then informed Yakon himself, and he lumbered off to stage two. Goku, Vegeta, Gohan, and the Supreme Kai encountered Yakon on the second level of Babidi's Spaceship during their descent to stop the awakening of Majin Boo.
After Vegeta eliminated Puipui, Goku squared off against Yakon. Babidi transported them to Yakon's homeworld, Planet Darkness, in order to give the beast an advantage. Yakon commented that he could see Goku even in the dark, only to be surprised when Goku effortlessly dodged his attacks and landed a blow of his own. Goku informed Yakon that eyesight was not necessary in order for him to feel his opponent's movements. He did have another means to see his opponent. Goku surprised Yakon (along with an onlooking Babidi and Dabura) by transforming into a Full Power Super Saiyan, lighting up the area in the process.
With his Super Saiyan energy emitting a tremendous amount of light, Goku informed Yakon that their dark environment no longer mattered. Yakon surprised Goku yet again, however, by sucking up his light (a delicacy to Yakon), reverting Goku to his base form. Upon discovering that Yakon literally ate light, Goku transformed into a Super Saiyan again. Delighted by the fact that he had another meal, Yakon began to suck up the light. Using Yakon's greed to his advantage, Goku countered by powering up to an enormous extent (Apparently showing Vegeta a glimpse of his Super Saiyan 2 powers, leading him to conclude that Goku, too, has assumed the transformation in the 7-year period after the Cell Games as he had.) and providing him with so much light that Yakon exploded as a result.
Dragon Ball GT
Yakon later made a cameo appearance during the Super 17 Saga in Dragon Ball GT when the barrier between Hell and Earth was breached. He caught Son Goten off guard, but was quickly dispatched by Trunks Brief.
Yakon displayed high defense, but also the ability to form mini duplicates of himself and fire an extremely potent energy beam from his mouth, in Dragon Ball Z: Buu's Fury.
Yakon appeared in Dragon Ball Z: Budokai Tenkaichi 3 as one of Babidi's Blast 2 attacks, Yakon Is Next!, in which Babidi summons him and he attacks their opponent by striking them with his sharp claws.
- Hikari Kyūshū – Yakon sucks up light energy, his favorite food, using the Hikari Kyūshū (光 吸収, Hikari Kyūshū) technique, thereby lowering his opponent's ki.
- Tobidasu Tsume – Yakon sports a large, retractable claw in each of his forearms to use the Tobidasu Tsume (飛び出す 爪, Tobidasu Tsume) attack.
- Japanese dub: Yoshiyuki Kono
- Ocean Group dub: Michael Kopsa
- FUNimation dub: Paul LeBlanc
- Latin American dub: Mario Sauret
- Yakon is the first character in Dragon Ball Z to be killed by Goku. It could be argued that Goku did not intentionally kill Yakon at all, but rather allowed Yakon to kill himself unintentionally by allowing him to eat far too much of Goku's energy. This trivia of course does not include all of the people that Goku kills in Dragon Ball as there were many, from talking Fish to Red Ribbon Army Soldiers to Piccolo Daimao.
- Yakon keeps the 'M' crest when he dies, while Vegeta and Dabura lose theirs when they die.
- According to Babidi, his power level is 800 Kili, little more than a fourth of Full Power Super Saiyan Goku's 3,000.