Stanley Uris is played by Ben Heller [who's only listed acting job is this movie] as a kid, and as an adult by Richard Masur [from Scavenger Hunt, The Thing, Mr. Boogedy, Timerider, Semi-Tough, My Science Project, Encino Man, License To Drive, and Multiplicity].
Stan has the hardest time accepting what's going on. It was him who Pennywise grabbed in the sewer, and only he and Henry Bowers saw the final fate of Belch. He was also the last one to see IT when they were kids, it appeared to him as a Mummy. When IT returned, Stan couldn't take the mental stress and killed himself. IT appeared to the others as Stan's head in the library fridge. You can explore the rest of InfiniteCoolness.com using the links at the top of the page, and if you're looking for a picture that's not here, try posting a request on the board. Thanks for stopping by!