Stephen C. Sillett (born March 19, 1968) is an American botanist specializing in old growth forest canopies. As the first scientist to enter the redwood forest canopy, he pioneered new methods for climbing, exploring, and studying tall trees. Sillett has climbed many of the world's tallest trees to study the plant and animal life residing in their crowns and is generally recognized as an authority on tall trees, especially redwoods (Sequoia sempervirens).