Son Gohan is the son of Goku and Chichi named after the man who found Goku and raised him from a young age. Gohan is first seen in the first episode of Dragon Ball Z as a young and nervous child. Over the course of the series he grows and matures to become one of the strongest fighters in the universe. Because Goku is a Saiyan and Chichi is a Human, Gohan is a Saiyan-Human Half-Breed. Gohan has appeared as a playable character in most of the Dragon Ball Z video games. He often appears as many different fighters at his different ages seen in the anime. The Gohan from Trunk 's timeline known as "Future Gohan" has also been a playable character in a few games including Dragon Ball Z: Tenkaichi 3 and Dragon Ball Z: Shin Budokai - Another Road.
Gohan's first combat experience comes against Raditz when he bursts out of Raditz's Saiyan Space-pod and launches a powerful attack. Seeing this, Piccolo takes Gohan from his parents and trains him for the coming of Vegeta and Nappa. During the fight between the two Saiyans, Piccolo is destroyed by Nappa while protecting Gohan. This triggered Gohan to rapidly increase his power into one attack which slightly weakened and enraged Nappa but drained all the strength out of Gohan. At this time, Goku returns and continues the fight against Vegeta and Nappa.
During the final fight between Goku and Vegeta, Vegeta has Goku severly injured and unable to fight. Gohan returns to help his father but is proven to be useless agaisnt Vegeta. His tail, which was previously removed by Piccolo for the safety of others, finally grows back. Because the full moon was out, this triggered Gohan to transform into his Oozaru form, which overpowers Vegeta.
Gohan's power and confidence increased as the Frieza saga progressed but was still unable to control and unlock his full potential of power. A friendship and close partnership with Krillin was formed and they both had to battle Captain Ginyu, who had performed his body change technique with Goku which proved to be emotionally difficult at first. Gohan fought against Frieza alongside Krillin, Piccolo and Vegeta while Goku was recovering after the battle with Captain Ginyu. Although Gohan didn't fight much, Gohan's outbursts in power proved to be useful at the most dangerous of times. The first being when Frieza had transformed into his second form and attacked Krillin. Believing Krillin was dead, Gohans power dramatically increased followed by a shower of Ki Blasts overwhelming Frieza. The second time is when Goku had transformed into a Super Saiyan and told Gohan to take Piccolo's unconscious body to the space shuttle and leave Planet Namek.
While Goku had the upperhand on the fight after transforming, he was caught by surprise by Frieza during a beam struggle which caused Frieza to throw an onslaught of attacks on Goku which made both Frieza and Gohan believe he had been defeated due to the disappearance of his power level. This worried Gohan and insisted he left the shuttle which was about to launch and fly back to the battlefield to find out what happened to his father. After being met by Frieza, he is told that Goku has been destroyed which outrages Gohan and throws a flurry of punches and a Ki Blast against Frieza. Goku's power level returned and continued the battle against Frieza telling Gohan to once again return to the space shuttle but before Gohan returned, he and all other beings on Namek apart from Frieza and Goku were transported to Earth following a wish granted by the Dragon Balls.
In preparation of the Androids arrival in three years time, Gohan trained with Goku and Piccolo. Another being created by Dr Gero unexpectedly appeared which after Goku recovered from his heart condition, he took Gohan to the Hyperbolic Time Chamber so they could train in preparation for t he battle against Cell. Knowing Gohan had the power 'deep down' to defeat Cell and become one of the strongest fighters in the universe, Goku made it his intention to unlock and control Gohan's full potential during these intense training sessions. During this time, Gohan became able to transform into a Super Saiyan but Goku believed that although his current state still wouldn't be enough to defeat Cell, Gohan still had the potential to defeat him. Goku realized he was right after seeing a very short glimpse of Gohan's Super Saiyan 2 transformation near the end of their training in the Hyperbolic Time Chamber.
During the Cell Games, Goku stepped down after fighting will Cell and declared that Gohan would be the next person to fight, much to the rest of the Z Fighter's shock but Goku remained calm and confident. After a short fight, Gohan told Cell that his power greatly increases when he is extremely angry and blinded by rage. Intrigued by this, Cell produces Cell Jr.'s to attack the rest of the Z Fighters extremely weakening Goku. With Gohan's anger increasing, the head of Android 16 whose body had been destroyed earlier in the Cell Games was thrown into the battlefield in front of Gohan who by this time was finding it hard to control his anger. Android 16 used his last moments as encouragement for Gohan to allow his anger to explode for his hidden power to be unleashed. At this time, Cell stamps on Android 16's head which acts as the final trigger. Gohans rage allowed him to finally transform into a Super Saiyan 2. He shows his new power by killing each of the Cell Jr.s with no more than one attack each.
In a final beam struggle, Gohan defeated Cell but lost his father in a sacrifice bid to save the planet from Cell's self-destruct explosion. At the time of the Cell Games, Gohan was deemed the strongest fighter in the universe being the only current Saiyan to achieve the Super Saiyan 2 transformation.
Gohan also plays a large role in the Buu saga. The story begins with him, matured into a teenager, attending high school and fighting crime under the guise of The Great Saiyaman. The daughter of Hercule; Videl, eventually finds out that Gohan is the Great Saiyaman and forces him to teach her how to fly. As the series progresses it becomes more and more obvious that they are falling in love with each other and they eventually get together.
When Buu is summoned, Gohan attempts to battle him, but he beats Gohan within an inch of his life and leaves him for dead. The Supreme Kai saves him, and takes him to his planet to become stronger by wielding the Z Sword. After some time training, he accidentally breaks the sword and releases the Elder Kai, who uses a magic ritual to finally unlock Gohan's true potential power--making him the strongest of all the Z fighters, even more powerful than Goku in his Super Saiyan 3 form. After having his full potential unlocked, fans dubbed him "Mystic Gohan". He returns to Earth to battle Buu, and dominates the fight until Buu absorbs Gotenks and Piccolo. Eventually, Buu absorbs Gohan too. He is rescued from the inside of Buu by Goku and Vegeta, but is killed in the subsequent destruction of Earth. He is later resurrected with the Dragon Balls, and is seen giving his power to Goku's giant Spirit Bomb.
After the Buu saga, Gohan eventually marries Videl, and has a daughter named Pan, who goes on to be a major character in Dragon Ball GT.