Stan Pines

Stanley Pines, also known as Grunkle Stan or simply Stan, is Mabel and Dipper's sly great-uncle Stan. He runs the Mystery Shack, a tourist trap full of questionable oddities. When he’s giving tours or asleep on the couch, Dipper and Mabel sneak out to explore the town’s secrets.

Personality
Dipper and Mabel's great-uncle, Grunkle Stan, is a gruff and miserly salesman who has finally managed to set up shop in a town with enough unsuspecting customers to sell his worthless knickknacks. His flair for showmanship is oddly hypnotizing, and thus he is able to make money by peddling the bogus trinkets and baubles in his store. His work ethic is mainly driven by his desire to make money, so when he's not generating an income, he's usually at home watching television. Even though he sends the twins on unpredictable and outrageous errands, he always has their best interests at heart and loves them unconditionally. Meanwhile, when he isn't busy trying to make a quick buck from his unsuspecting customers, Grunkle Stan guards his own secret that might hold the key to unlocking the mystery of Gravity Falls.

Season 1
Sometime during the month of June, Stan's great niece and nephew were sent from Piedmont, California to stay with him for the summer. Stan immediately puts them to work in his house-turned tourist trap, the Mystery Shack. He has a secret door behind the vending machine in house, where he may be hiding something.

Trivia

 * Grunkle Stan has a tattoo of an arrow piercing a heart on his back.
 * He has been to jail in Colombia.