Benjamin Silliman (August 8, 1779 – November 24, 1864) was an American chemist and science educator. He was one of the first American professors of science, the first science professor at Yale, and the first person to use the process of fractional distillation in America. He was a founder of the American Journal of Science, the oldest continuously published scientific journal in the United States.

Silliman was born in a tavern in North Stratford, now Trumbull, Connecticut, to Mary (Fish) Silliman (widow of John Noyes) and General Gold Selleck Silliman. He was born in August 1779, several months after British forces took his father prisoner and his mother had fled their home in Fairfield, Connecticut, to escape 2,000 British troops who burned Fairfield center to the ground.

Silliman was educated at Yale, receiving a B.A. degree in 1796 and a M.A. in 1799. He studied law with Simeon Baldwin from 1798 to 1799 and became a tutor at Yale from 1799 to 1802. He was admitted to the bar in 1802. That same year he was hired by Yale President Timothy Dwight IV as a professor of chemistry and natural history. Silliman, who had never studied chemistry, prepared for the job by studying chemistry with Professor James Woodhouse at the University of Pennsylvania in Philadelphia. In 1804, he delivered his first lectures in chemistry, which were also the first science lectures ever given at Yale. In 1805, he traveled to University of Edinburgh for further study.

Returning to New Haven, he studied its geology. His chemical analysis of a meteorite that fell in 1807 near Weston, Connecticut, was the first published scientific account of an American meteorite. He lectured publicly at New Haven in 1808 and came to discover many of the constituent elements of many minerals. Some time around 1818, Ephraim Lane took some samples of rocks he found at an area called Saganawamps, now a part of the Old Mine Park Archeological Site in Trumbull, to Silliman for identification. Silliman reported in his new American Journal of Science, a publication covering all the natural sciences but with an emphasis on geology, that he had identified tungsten, tellurium, topaz and fluorite in the rocks. He played a major role in the discoveries of the first articulated fossil fishes found in the United States, which he discovered in Newark Supergroup deposits near Connecticut, and were later described as the genera Redfieldius and Semionotus. In 1837, the first prismatic barite ore of tungsten in the United States was discovered at the mine. The mineral sillimanite was named after Silliman in 1850. Upon the founding of the medical school, he also taught there as one of the founding faculty members.

In 1833 he discussed the relationship of Flood geology to the Genesis account and also wrote about this topic in 1840.

Silliman was an early supporter of coeducation in the Ivy League. Although Yale would not admit women as students until over 100 years later, he allowed young women into his lecture classes. His efforts convinced Frederick Barnard, later president of Columbia College, that women ought to be admitted as students. "The elder Silliman, during the entire period of his distinguished career as a Professor of Chemistry, Geology and Mineralogy in Yale College, was accustomed every year to admit to his lecture-courses classes of young women from the schools of New Haven. In that institution the undersigned had an opportunity to observe, as a student, the effect of the practice, similar to that which he afterward created for himself in Alabama, as a teacher. The results in both instances, so far as they went, were good; and they went far enough to make it evident that if the presence of young women in college, instead of being occasional, should be constant, they would be better."

American historian David McCullough mentions in his book about early 19th century Americans in Paris that in 1825 Silliman, while on a tour of Europe conferring with other scientists, encountered his former Yale science student Samuel Morse in the Louvre. As professor emeritus, he delivered lectures at Yale on geology until 1855; Silliman had been the first person to use the process of fractional distillation, and, in 1854 his son Benjamin Silliman Jr became the first person to fractionate petroleum by distillation. In 1864 Silliman noted oil seeps in the Ojai, California, area. In 1866, this led to the start of oil exploration and development in the Ojai Basin.

Silliman pioneered the mass production of carbonated water and helped popularize it in the United States. In 1806, he purchased a Nooth apparatus and opened a soda fountain in New Haven. He marketed his mineral waters for their medicinal properties.