No, the Hubble Space Telescope did not discover Neptune. Neptune was discovered in 1846 by Urbain Le Verrier and John Couch Adams, using mathematical calculations and observations of Uranus's orbit. The Hubble Space Telescope was launched in 1990, long after Neptune's discovery.

Hubble has, however, provided incredibly detailed images and observations of Neptune, helping us learn more about its atmosphere, moons, and rings.