William Vacchiano (May 23, 1912 – September 19, 2005) was a trumpeter and trumpet instructor.

Originally from Portland, Maine, Vacchiano studied trumpet at age 12. At 14 years old, he was playing in the Portland Symphony. For five years (1930-1935), he studied under Max Schlossberg at the latter's studio in The Bronx.^[1] He joined the New York Philharmonic in 1935 as third/assistant principal trumpet and appointed principal trumpet in 1942 by Bruno Walter. He taught at the Juilliard School for 67 years (1935-2002). He was also a professor at the Mannes College of Music from 1937–83 and the Manhattan School of Music from 1935-2002. His students included Wynton Marsalis, Philip Smith, Charles Schlueter, Gerard Schwarz, Manny Laureano, and Miles Davis.

His obituary in The New York Times quoted him saying:

"This, to me, is happiness. When I feel bad I go down to the studio in my house, I pick up my horn and I'm in seventh heaven. That's what music should be like."