DrB is correct it is NOT Scar:
As Mufasa's brother, Scar was next in line for the throne until Simba's birth, and he is obsessed with the need to possess it. Although Scar hides his plot with concern for Simba's safety, this evil, cunning betrayer is really Simba's and Mufasa's enemy-- a fact which the great-hearted Mufasa realizes too late.
well, if I'd been asked for the villain of course I would have said Scar. I've only watched that film 63 times (it came out when my kids were just the right age to watch a video 30 times). Ask me who the bird was! or the monkey! or Simba's girlfriend! Or the warthog! or the meerkat!