Allium howellii is a North American species of wild onion known by the common name Howell's onion. It is endemic to California.
Allium howellii is a tall onion plant, producing a stem which may exceed half a meter in height from a reddish-brown bulb one to two centimeters long. There is a single cylindrical leaf about as long as the stem. The inflorescence holds up to 100 dark-veined lavender to white flowers, each under a centimeter long.
Several varieties have been named:
Howell's onion grows in the granite and serpentine soils of several mountain ranges, hills, and valleys from San Joaquin County to San Bernardino County.