Stanley "Stan" Pines (voiced by Alex Hirsch) better known as Grunkle Stan, is Mabel and Dipper's sly, cranky great-uncle. He runs the Mystery Shack, a tourist trap full of questionable oddities. When he's giving tours or sleeping on the couch, Dipper and Mabel are usually sneaking out to explore the town’s secrets, though Grunkle Stan may have some of his own mysterious secrets.
Dipper and Mabel's great-uncle, Grunkle Stan, is a gruff, selfish, greedy and miserly salesman who has finally managed to set up his shop in a town with enough unsuspecting customers to sell 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 is guarding his own secret that might hold the key to unlocking the mystery of Gravity Falls. Grunkle Stan would visit the twins and and the twins would visit him sometimes he would go on adventures with the cyberchase fighters.
- Jeffrey, Jaden and Hiccup will meet Grunkle Stan in Jeffrey, Jaden, Hiccup & Friends go to Gravity Falls.
- Twilight, Sunset and Kyle will meet Grunkle Stan in The Rainbooms & The Z Fighters go to Gravity Falls after the events of "My Little Pony Equestria Girls: Legend of Everfree" and "Equestria Girls: Magical Movie Night".
- During the adventure series, Grunkle Stan is also putting Grim to do the chores like he does on Dipper.