Real People who Look Like Cartoon Characters

Cartoon character designers generally start designing a character based on a single personality attribute that the character will portray throughout the animation. For example, if the character has a dorky personality, the character designer will try to portray this by creating a dorky-looking character. For villains and heroes, the character designer will give the character's physical appearance the appropriate attributes. 

Sometimes character designers need inspiration, and so they'll look around and observe people, finding facial shapes and physical characteristics that incorporate the essence of the character they are creating. These attributes of real people find their way not only into the character design, but into the animation, personifying the characters and making it easy for audiences to empathize with them.

People who Look Like Pixar Characters
Pixar animations are known for having lovable, believable characters, and now people are discovering that Pixar artists have a knack for creating characters that resemble living people. These people have taken pictures of themselves with their look-alike characters and posted the pictures online.

Above: Carl Fredricksen, a Pixar character from the movie "Up" is shown on the left, and on the right, a real live old guy who looks just like his animated counterpart. [source]

Above: This Asian kid looks identical to the cartoon character Russell from Pixar's lovable animated movie "Up". The only difference is the color of the kid's boy scout scarf. [source]

Above: On the left is the character Linguini from the Pixar animated film "Ratatouille". The real guy on the right looks just like his cartoon doppelganger, right down to the sweet-hearted smile. [source]

Beavis and Butthead in Real Life
Beavis and Butthead are two cartoon characters that were created by Mike Judge in 1992. The characters found a home on MTV, which popularized the duo. Within weeks, Beavis and Butthead had found their way into the hearts and homes of millions of people. Their dorky laughs and dumbass catch phrases could be heard in school and college campuses across the world.
The characters are essentially caricatures of two below-average American teenagers who constantly get themselves into trouble with teachers, law keepers, criminals and pretty much every person they come across. The characters are so highly stylized that it's almost impossible to visualize them as real human beings, but here they are, in the flesh:

Above: One of Beavis's signature character attributes is the size of his head. Although Chris Kemp's nostrils could use some stretching, he totally looks like Beavis in many other ways. [source]

Above: Zach from "Little People, Big World" looks just like the cartoon character Butthead. [source]