Gryzzl is an internet company that is headquartered in Pawnee near the end of the show. It is a takeoff on Google and other Silicon Valley companies.
Gryzzl first appears in the season 6 finale Moving Up (Parts 1 & 2), when Ben Wyatt discovers that they are playing The Cones of Dunshire. Ben challenges them to a Cones of Dunshire match, wins, and in the process gains free WiFi for the town. Gryzzl subsequently opens a corporate office in Pawnee.
Gryzzl are the primary antagonists of the Season 7 story arc, which centers around them trying to purchase the Newport land, with the assistance of Leslie's former co-workers Donna Meagle and Ron Swanson.
Things come to a head in the episode Gryzzlbox, when Gryzzl delivers "Gryzzlboxes" to Pawnee residents full of their favorite things via drone. This leads to the revelation that Gryzzl has been using data mining to learn the wishes of Pawnee residents, which in turn leads to Donna and Ron abandoning Gryzzl and siding with Leslie.