The Cone Nebula (also known as NGC 2264) is an H II region in the constellation of Monoceros. It was discovered by William Herschel in 1785. The nebula is located about 800 parsecs or 2,600 light-years away from Earth.

The Cone Nebula is part of the nebulosity surrounding the Christmas Tree Cluster. The designation of NGC 2264 in the New General Catalogue refers to both objects and not the nebula alone.