William Bartram (April 20, 1739 -July 22, 1823) was an American naturalist, the son of John Bartram.

Bartram was born in Kingsessing, Pennsylvania. He accompanied his father on many of his travels, to the Catskill Mountains and Florida, and was noted at a young age for the quality of the drawings he produced of botanical specimens his father had gathered. He also had an increasing role in the maintenance of his father's showcase garden, and added several rare species to it.

In 1773 he set off alone on a four-year journey through eight southern colonies. He made many drawings and took notes on the native flora and fauna, and the native American Indians. Bartram went on another expedition through Florida, Georgia and the Carolinas extending through most of the 1780s. During this period he compiled the most complete list of American birds up to that time.

Frontispiece and title page of "Travels"

Upon his return Bartram published his journal in 1791, under the title Travels through North and South Carolina, Georgia, East and West Florida, the Cherokee Country, etc. which was considered at the time to be one of the foremost books on American natural history. In addition to its contributions to scientific knowledge, Travels is noted for its original descriptions of the American countryside, which in turn influenced many of the Romantic writers of the day. William Wordsworth and Samuel Coleridge are known to have read the book, and its influence can be seen in many of their works.

In 1802 Bartram met the school teacher Alexander Wilson and began to teach him the rudiments of ornithology. Wilson's American Ornithology includes many references to Bartram and the area around Bartram's Gardens.

Bartram spent most of the final decades of his life in quiet work and study at his home and garden in Kingsessing, refusing several requests to teach botany and declining an invitation to accompany the Lewis and Clark Expedition. He died at his home at the age of 84.