Mistissini (Cree: ᒥᔅᑎᓯᓃ, romanized: Mistisinî meaning Big Rock) is a Cree town located in the south-east corner of the largest natural lake in Quebec, Lake Mistassini. The town is inside the boundaries of the Baie-James Municipality and is the second largest Cree community with a population of 3,731 people in 2021. The surface area of the town is 807.75 square kilometres (311.87 sq mi) (Category I land, as defined in the James Bay and Northern Quebec Agreement).
Mistissini is part of the Grand Council of the Crees (Eeyou Istchee) and the Cree Regional Authority. The Cree School Board and the Cree Construction Company have their head offices here.