Dennis Dreith (June 15, 1948 —) is a motion picture music composer, arranger, and conductor. He is also known as an influential advocate for studio musician's rights.
A native Californian born in Glendale, Dreith showed a talent for music at an early age. He learned to play a variety of keyboard and reed instruments while still in his teens. He formed a jazz combo in the late 1960s; the late music promoter Raymond D. Bowman (1917–2001) scheduled them for a number of Monday night concerts at the legendary Ice House in Pasadena.