William Penn Brooks (November 19, 1851 – March 8, 1938) was an American agricultural scientist, who worked as a foreign advisor in Meiji period Japan during the colonization project for Hokkaidō.

[1] Brooks' collegiate activities are notable because of his role in founding Phi Sigma Kappa fraternity along with five fellow students.

Yet among all these, it was his role as a Founder of Phi Sigma Kappa fraternity in his Sophomore year by which his name is best remembered today.

Brooks arrived in Sapporo in January 1877, shortly before Clark left the school and only a few months before the Japanese government crushed the Satsuma rebellion, the last opposition to its policy of modernization.

Immediately after his arrival, he began to deliver lectures on agricultural science and took charge of the directorship of the experimental fields.

[3] Brooks returned to the United States in October 1888 after having received the Order of the Rising Sun (4th class) from Emperor Meiji, and accepted a position at Massachusetts Agricultural College as a lecturer, and for two years, as president (1905–06).

In 1893, at the twenty-year anniversary of the founding, Brooks was appointed a committee of one to prepare an updated constitution for the order, which was adopted unanimously.

[1]: 92  Brooks continued to attend occasional meetings and lend his voice to policy debates during his older years.