Castilleja is a genus of about 200 species of annual and perennial herbaceous plants in the family Scrophulariaceae, native to the west of the Americas from Alaska south to the Andes, and also northeast Asia. They are commonly known as Indian paintbrush or Prairie-fire. They are semi-parasitic on the roots of grasses.

One of the species of this genus, the Indian paintbrush (Castilleja mutis) was adopted on January 31, 1917 as the Wyoming state flower.

Castilleja School is a private 6-12 all-girls' school in Palo Alto, CA.