Mark (or Mr. Satan or Hercule, depending on the versions) is a main character in Dragon Ball Z and Dragon Ball GT.
The Tenkaichi Budokai champion, Mr. Satan is widely known all over the world as the strongest man alive and a celebrity hero. He is the father of Videl, the father-in-law of Gohan, and the maternal grandfather of Pan. He first appears during the Cell Saga, to fight Cell who started attacking the planet. However, Satan is too much weak (especially compared to the Z Warriors) and gets thrown out of the ring without even hurting his "opponent," who merely paid attention to him.
During the following fights, Mr. Satan pretends to be ill, and that all the others are cheating. He, however, accepts to take Android 16's head to Gohan, which proves useful, since it convinced the boy to fight Cell with all his power. After the fights are over, Satan takes credit for killing Cell, and is labeled a hero.
Years later, Satan is called again to fight Majin Buu, and again is too weak to defeat him. Instead, he manages to become Boo's friend, and convinces him to stop killing. Though Boo later mutates into an even more dangerous monster, neither him nor Satan forget about their previous friendship. Thanks to this link and to his newfound courage (mostly when he starts believing the whole story is a simple dream) Satan becomes a suprisingly important ally to the Z Warriors, helping them to defeat Pure Majin Boo once and for all.
Satan again takes credit for the victory, but still remains friends with the fighters and the good Boo, who comes to live with him.
Satan is the strongest "normal" human of the series, and has an incredible luck, since he not only survives all the dangers he goes through, but also gains fame for most of the heroes' acts. Though he is extremely arrogant, cunning, a good liar and often clueless about what is going on, he still is very good-hearted and heroic when he has to be.
He is voiced by the late Daisuke Gōri and the late Unshō Ishizuka in the Japanese version of the anime, and by Chris Rager in the English version of the anime.
Dragon Ball Z
Mr. Satan first appears during the Cell Games as a preening challenger of Cell. According to his backstory, once Goku and his companions stop attending the World Martial Arts Tournament, he starts winning the annual World Martial Arts Tournaments and becomes the reigning champion for many years. Mr. Satan attempts to fight Cell but is swatted away in one hit. In spite of this, he is given credit for Cell's death by the media and celebrated as a hero.
Years later, he is revealed to be the father of Videl, the would-be love interest of Gohan, and is still revered throughout the world of Dragon Ballas a hero. He later encounters and befriends Majin Buu: after convincing him of the error of his murderous ways, the benevolent influence within Buu moves the creature to reform, leading him to expel his evil tendencies which become a different lifeform altogether. This aspect of Buu is identical in appearance to his chubby progenitor, although any malevolent behavioral traits previously displayed are gone. He is also much weaker in power, and lacks some of the original Majin Buu's unique capabilities.
As one of the few survivors of the evil Buu's destructive rampage which culminated in the destruction of Earth, Mr. Satan escapes to the Supreme Kai's sacred realm along with Goku and his remaining associates. When Goku is on the verge of losing the final fight against Buu's evil incarnation, Mr. Satan rallies the people of Earth to turn the tide in Goku's favor by directing them to contribute their energy to Goku's Genki-Dama, an energy sphere attack created by gathering energy from surrounding animals, nature and humans. Following the demise of the evil Buu by Goku, his benevolent counterpart moves in with Mr. Satan and his pet labrador retriever Bee, and goes by Mr. Buu.
Dragon Ball Super
Mr. Satan again appears as a supporting character in Dragon Ball Super, where he is often seen in the company of Mr. Buu. Mr. Satan essentially serves as the caretaker of his friend as Buu has a childlike personality. He is depicted as having grown immensely wealthy due to the monetary rewards he received from his false claims of successfully defending Earth from multiple external threats. In one episode of the anime version, Mr. Satan enacts an imaginary fight with Beerus, the God of Destruction, in a televised retelling of the series' in-universe events where he embellishes himself with the ability to power up as a Super Saiyan.
Dragon Ball GT
Mr. Satan makes minor appearances in the Dragon Ball GT anime series, where he is protected from the extraterrestrial villain Baby's influence by Majin Buu and later his successor, Uub.
Although very weak when compared to Goku and the others, Mr. Satan is a skilled martial artist whose strength exceeds that of regular people.His strength is much greater than that of "normal" humans like the evil gunmen Van Zant and Smitty, and it is higher than that of a martial artist like Spopovich (before Babidi increases his power). Mr. Satan also seemingly has superhuman levels of strength and speed, demonstrated when he moves so fast he vanishes from sight making it appears like he is teleporting (to Van Zant - an ordinary human), pulls four buses single-handedly and punches a hole in one (in the anime), tearing multiple phone books in half, and crushes fourteen tiles simultaneously with a chop. In his match against Spopovich in the 24th World Tournament (only in the anime), he displays the ability to leap very high into the air and land with no apparent damage or difficulty, and effortlessly sends Spopovich, who is much larger and more muscular than him, flying with a single kick. Mr. Satan also survived a fight with Mercenary Tao (albeit with extreme injury) while training at Satan Castle (surviving a battle with Tao which resulted in the death of his martial teacher), something not even the likes of General Blue or Bora were capable of. However, according to Gohan, his skills are below that of his daughter Videl, who has a basic understanding of ki and flight, and takes training more seriously than he does.
He is able to survive being knocked into a mountain by Perfect Cell (although Piccolo notes that Cell did not want to expend any effort into attacking the likes of Satan), and even a light punch to the face from Kid Buu, though these instances are likely intended for comic relief. In Dragon Ball GT, he also survives a kick from Omega Shenron, though again for comedic effect and, like with Cell, it's possible that Omega Shenron didn't exert any real effort into the attack.
All in all, Mr. Satan's fighting capabilities are similar to other normal Earthling martial artists seen in Dragon Ball like Nam and King Chappa who while not as strong as Goku and the Z Fighters (who, with all fairness, either have access to training a 'typical' human would generally never have or aren't human) are still stronger than normal untrained humans and possess superhuman capabilities such as superhuman strength and speed (allowing them to use techniques like Rapid Movement and the Afterimage Technique).
- Mr. Satan fought Dan Hibiki in the DEATH BATTLE and won.