Roar!

Big cats or wild cats, along with domestic cats, are members of the family Felidae. Tigers, lions, leopards, jaguars and cheetahs are the bigger members of the Felidae family, and the first four are the four well-known species of the Panthera genus. They are divided to more species and subspecies, usually based on their physical characteristics and habitats or locations in which they live in. Bali Safari, 25th of September 2010.

Panthera leo or lion are quite often associated as the greatest big cat existing, or, they are also usually referred as 'King of the Jungle'. Lions are, however, not the largest member of the Panthera genus, tigers are. However, lions, or exactly male lions, are the only species of the big cat subfamily that have manes. Their tails are also different from the other big cats--it has a tuft of fur at the end. They're also different from the other big cats, since they don't live a solitary life like the others, but live in a blood-related big group called prides.
Wait. Oh. So that's why they're the kings.

(By the way, they weren't as yellow or orange as Simba and his pride. Their coat is more tawny or golden.)

References.

1. All the wildlife shows I watch everyday on NatGeoWild and Animal Planet.

2. http://a-z-animals.com/animals/lion/