According to A Tale of Two Brothers from The Lion King: Six New Adventures, Scar was given the name "Taka" as the younger son of Ahadi and Uru. His older brother Mufasa was chosen to be king over him, a decision which caused the young lion much angst 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.
When Uru proposed to leave Pride Rock for a new food and water supply, Taka went on a patrol with his father and older brother. While they were patrolling the Pride Lands, the three ran into Rafiki, a traveling baboon who was being plagued by the hyena trio but then he was rescued by Ahadi and his sons Mufasa and Taka, close behind him. Though Taka acted bored and commented that they should have let the baboon die, Ahadi welcomed Rafiki into the Pride Lands and let him spend the night at Pride Rock. When Mufasa stayed by his father's side throughout the ordeal, Taka wandered off, feeling unconcerned with his father's doings.
Later that night after his brother didn't support him against his father, 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 promised to take his sons hunting, but a group of angry Pride Landers stalled him, and he was forced to cut the hunting trip short a change of events which that does not 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 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 decided to pursue his kingly duties, leaving Taka alone to hunt with Mufasa.
Before the hunt, Taka plotted with the hyenas Shenzi, Banzai, and Ed to get Mufasa in trouble with Ahadi so that their father might have second thoughts about Mufasa becoming king. Once he agreed with the hyenas, he lead Mufasa to a water hole, where an antagonistic buffalo named Boma was hogging one of the only water sources left after the start of the drought, when Mufasa attempted to reason with him, Taka roars with an ultimatum: and told Boma that he's enforcing the Kings orders telling him that if he doesn't listen to Mufasa he will challenge him to a fight. Boma then becomes enraged because he tricked Mufasa into angering Boma. When the buffalo began to chase Mufasa, Taka only laughed at his brothers fear until the other members of Boma's herd began to attack the young lion giving him his scar.
Just in time, Ahadi appeared on the scene to stop the buffaloes, and Ahadi helped Mufasa take Taka back to Pride Rock with an elephants trunk, where Rafiki cared for him until he was patched up enough to speak and Taka's eye was wounded from the buffalo herd which it will never heal and he will carry a scar with him for the rest of his life. Once recovered, Taka was told by his father, that the scar he had earned will serve as a reminder of his recklessness. When Mufasa asked his brother why he made Boma angry, Taka only admitted that he wanted to embarrass Mufasa and to get even with Ahadi for breaking his promise, and Ahadi warned his son to keep his anger at bay. At first Taka was angry, then Taka at last accepted his father's words and asked to be called "Scar" from now on as another reminder of his horrible decision to which he then promises not to forget what happened that day.
It has been revealed that, as usual for the second-born cub of the monarch, Scar was tasked with leading the Lion Guard when he was younger and was given a power called the Roar of the Elders, which, when used, would cause the Great Kings of the Past to roar with him. However, the power got to Scar's head, and he believed that with this power, he should be king instead of Mufasa. So he planned to dethrone Mufasa by using the Roar of the Elders. When the rest of the Lion Guard refused to aid him in his plot, Scar destroyed them and thus lost his power, as the Roar of the Elders was not meant to be used for evil. In the years that followed the Lion Guard's downfall, Scar focused his life on striving for his older brother's throne and continued to plot schemes with the hyenas to rule the Pride Lands.
As far as the coloring goes, Scar has dusty orange fur, while his muzzle, paws, and underbelly are all tan color. His mane is thinner and sleeker than those of the other males, colored a coal black that appears dark brown in the sunlight, with the fur on his elbow joints and the tuft of his tail matching the black of his mane. His chin fur is scruffier and pointed down in a distinctive goatee, while his eyebrows are black and considerably thick. Unlike most lions in his pride, Scar possesses dark scarlet eyeshades, an angular nose, and neon-green eyes. His claws are always extended, something the Outsiders later emulate. Finally, a small, thin, red scar runs over his left eye, earning him his name.
His personality was the opposite of Mufasa's. He was mean, envious, cruel and evil. His jealousy stemmed from the fact that his older brother Mufasa was chosen to be King. Scar was so hungry for power that he resorted into removing his own family permanently and destroying the kingdom. It was his thirst for power that caused him to lose the Roar of the Elders. He didn't believe in the Circle of Life concept and cared only for himself and his own glory. He was also a great orator and incredibly insecure, as he never wanted to hear the name of his brother mentioned after he took the throne.
According to The Rise of Scar play set, it has been announced that Scar will be a new villain for The Lion Guard in Season 2.
David Oyelowo will do the voice of Scar in The Lion Guard.