A knish is a traditional Ashkenazi Jewish snack food consisting of a filling covered with dough that is typically baked or sometimes deep fried.

Knishes are often purchased from street vendors in urban areas with a large Jewish population, sometimes at a hot dog stand, or from a butcher shop. They are still strongly associated with New York City cuisine, possibly because of the iconic Yonah Schimmel's Knish Bakery restaurant, located on the Lower East Side of Manhattan, traditionally a Jewish neighbourhood. Knishes were popularized in North America by Ashkenazi Jewish refugees from the Pale of Settlement (mainly from present-day Belarus, Lithuania, Ukraine, and eastern Poland).

In most traditional versions, the filling is made entirely of mashed potato, kasha (buckwheat groats), or cheese. Other varieties of fillings include beef, chicken, sweet potatoes, black beans, or spinach.

Knishes may be round, rectangular, or square. They may be entirely covered in dough or some of the filling may peek out of the top. Sizes range from those that can be eaten in a single bite hors d'oeuvre to sandwich-sized.