Thiells is a hamlet located in the town of Haverstraw in Rockland County, New York. It is located along Harriman State Park. The hamlet is located about 35 miles from New York City.

Thiells has a population of more than 4,500 residents. The hamlet has a total land area of 1.9 square miles. The hamlet is located at an elevation of over 270 feet above sea level.

Thiells is home to the Philip J. Rotella Golf Course and North Rockland High School.