Scar is the main antagonist in The Lion King.
As revealed in the book ''A Tale of Two Brothers'', Scar was given the name "Taka" meaning "dirt" in Swahili as the younger son of his parents Ahadi and Uru. Taka was upset because his older brother Mufasa was chosen to be the king over himself, a decision which caused the young lion much sadness and distanced him from his father and older brother. Over time, Taka came to resent Ahadi for favoring Mufasa and for choosing kingly duties over spending time with his sons. One day, Taka went on a daily patrol with his father and older brother when Taka was just an adolescent. While they were patrolling the Pride Lands, the three ran into Rafiki, a traveling baboon who was being plagued by the hyena trio until he was saved by Ahadi, along with his two sons Mufasa and Taka. After the departure of the hyenas and talked about Rafiki's mission, Ahadi invited Rafiki into the Pride Lands and let him spend the night at Pride Rock. Even after Taka acknowledged that they should have let the baboon die there. When Mufasa stayed by his father's side throughout the ordeal, Taka wandered off, feeling unconcerned with his father's doings. Later that night, Taka set a cobra on Mufasa, hoping to kill his brother in his sleep, but Rafiki thwarted the plan. The following day, after the attempted murder Ahadi had promised to take his sons out hunting, but a group of angry Pridelanders had stalled him, and he was forced to cut the hunting trip short a change of events which that doesn't settle well with Taka. Though Mufasa understood why his father made that decision, Taka reacted with outrage and accused his father of always finding other things to do when they were supposed to spend time together. In answer to his son's protests, Ahadi attempted to explain that his brother Mufasa understood the pressures of ruling a kingdom, but Taka's temper only flared, and he accused Ahadi for favoring Mufasa. Despite the young lion's animosity, Ahadi has decided to disregard his son's anger and pursue his kingly duties, by leaving Taka alone to hunt with Mufasa.
Before the hunt, Taka told Mufasa that he had something to do first. A suspicious Rafiki has decided to follow him and witnessed him devising a plan with the hyenas Shenzi, Banzai and Ed, at a dry hole to get Mufasa in trouble with Ahadi so that their father might have second thoughts about Mufasa becoming the next king. He lead Mufasa to a water hole, where a greedy buffalo named Boma was hogging one of the only water sources left after the start of the drought, and when Mufasa tried reasoning with him, Taka interjects with an ultimatum: and told Boma that he must either clear out by order of the King, or challenge Mufasa to a fight. Boma then becomes enraged as he tricked Mufasa into angering Boma. When the buffalo began to chase Mufasa and Rafiki, Taka only laughed at his brother's fear until the other members from Boma's herd began to attack the young lion causing him to be knocked unconscious and give him his scar.
Just in time, Ahadi came to the rescue with a herd of elephants to stop the buffaloes from attacking his sons, and an unconscious Taka was taken back to Pride Rock with the help of an elephant, where Rafiki cared for him with herbs until he was patched up enough to speak and Taka's eye was wounded from the buffalo herd during the attack which it will never heal and he will carry a scar with him for the rest of his life. Once recovered under Rafiki's care, Taka was chastised by his father, who told him that the scar he earned will serve as a reminder of his recklessness. When Mufasa questioned his brother to ask why he'd made Boma angry, Taka only admitted that he wanted to embarass Mufasa and get even with Ahadi for breaking his promise to go hunting with him, and Ahadi warned his son, to keep his anger at bay and let his wound serve as a reminder of his mistakes. At first Taka was angry, but then Taka at last accepted his fathers words, and he asked to be called "Scar" from now on as a reminder of his mistake which he then promises not to forget what happened on that day.
In his youth, Scar was tasked with leading the Lion Guard before his nephew Simba was born, and was given a power called the Roar of the Elders by the Great Kings of the Past. Which when used he summoned the Great Kings of the Past, to roar along with him. However the power got to Scar's head, and he believed that with this power he should be the king instead of Mufasa. So he planned to employ the rest of his Lion Guard to help him dethrone Mufasa, by using the Roar of the Elders. But when the rest of the Lion Guard refused to aid him in his plot, Scar destroyed them by using the Roar and because that act proved that Scar had used his powers for evil, the Kings of the Past removed the Roar from Scar. After many years of the Lion Guard's downfall, Scar continued to plan for Mufasa's throne and plot schemes with the hyenas to rule the Pride Lands.