He was voiced by Jeremy Irons.
Following the birth of Simba, Scar immediately plots to kill the young prince and his father. He sympathises with the scavenging hyenas that dwell in the Elephant Graveyard beyond the Pridelands' borders and has promised them new territory and more food if they serve him. Scar's first plot against Simba and Mufasa is put into action when he tells his impressionable nephew about the Elephant Graveyard. Though he was forbidden to go there, Simba and his friend Nala both run off into the dismal valley of bones only to be confronted by Shenzi, Banzai and Ed, three of Scar's hyena underlings. Simba and Nala are rescued by Mufasa, but the next day Scar hatches another plan to kill both Simba and Mufasa.
Scar leads Simba into a gorge and tells him to wait there for Mufasa to arrive, claiming that his father has a "surprise" for him. He also encourages Simba to practice his roar while waiting, and as Simba waits alone in the gorge, Banzai, Shenzi and Ed attack a herd of wildebeest grazing just above the gorge. The wildebeest are sent stampeding into the gorge and Simba flees for his life. Scar tells Mufasa about the stampede and follows him back to the gorge to oversee his brother's demise. Mufasa manages to save Simba but falls back into the stampede, but manages to leap out again on to a cliff face. Mufasa sees Scar sitting on the cliff and begs for help, but Scar grasps his brother's paws only to throw him back down into the gorge. Simba does not see Scar commit the deed, but after the wildebeest have gone he goes back down into the gorge to find his father's lifeless body.
Scar approaches the crying Simba, stating that it's the cub's fault that Mufasa is dead. Scar urges the guilt-ridden Simba to run away from the Pridelands and never return, then tells his hyena cohorts to kill the cub as he flees. The hyenas fail to catch Simba but keep that fact to themselves since Simba is unlikely to ever come back. With Simba in exile and Mufasa dead, Scar becomes the king of Pride Rock and allows the hyenas to move in to the Pridelands. In a few years, the Pridelands' former beauty and splendour are gone; all the lakes have dried up, the vegetation has withered and died and the prey animals that haven't been hunted and killed have all fled. Scar had sought power for so long, but it is clear to everyone that he is neither a benevolent nor even a competent ruler.
One day, a grown-up Simba returns to the Pridelands accompanied by his former best friend now mate Nala and his jungle friends Timon and Pumbaa. When he confronts his uncle, Scar tells Simba to admit his responsibility for Mufasa's death. However, after cornering Simba and leaving him hanging off the edge of Pride Rock, Scar admits the truth to Simba and tells him that he had killed Mufasa. This revelation immediately spurs Simba into pouncing on his uncle and forcing him to admit the truth to all the lionesses. With the truth revealed, a battle erupts between the lions and hyenas with the vegetation surrounding Pride Rock set on fire by a lightning strike.
Scar and Simba face each other in a final showdown. Though Simba is tempted to kill his uncle, he gives Scar the chance to leave the Pridelands in exile. Scar responds by pawing hot ashes in Simba's face and attacking him, but Simba defeats Scar by bringing up his hind legs as Scar pounces on him, lifting him up and over and sending him falling off a rocky ledge.
Scar picks himself up from the fall and finds Banzai, Shenzi and a dozen other hyenas surrounding him. Earlier, as Scar pleaded to Simba for his life, he stated that the hyenas were the "real enemy". The hyenas had realised by then that Scar was a terrible king who hadn't lived up to his promises and they turned on him. Scar begged the hyenas to let him explain himself, but the hungry scavengers were only interested in their next meal and pounced on him.
Scar's death occurs off-screen and only his shadow is seen being pounced upon by hyenas just before flames rise over the screen.