William Sanford "Bill" Nye (born November 27, 1955, Washington, D.C.), popularly known as "Bill Nye the Science Guy", is an American comedian, television host, science educator and mechanical engineer. He is best known as the host of the children's science show Bill Nye the Science Guy (1993–1997) and for his many subsequent appearances in popular media as a science educator.

Nye was born and raised in Washington, D.C. as a fourth-generation Washingtonian on his father's side. After attending Alice Deal Junior High in the city, he was accepted to the private Sidwell Friends School on a partial scholarship, graduating in 1973. He studied mechanical engineering at Cornell University's Sibley School of Mechanical and Aerospace Engineering, where one of his professors was Carl Sagan, and graduated with a bachelor's degree in 1977.

Nye began his career in Seattle at Boeing where, among other things, he starred in training films and developed a hydraulic pressure resonance suppressor still used in the 747. Later, he worked as a consultant and in the aeronautics industry. Nye told the St. Petersburg Times in 1999 that he applied to be a NASA astronaut every few years but was always rejected.