William Henry Allen was born in Readfield, Maine on March 27, 1808 to Jonathan and Thankful Allen. To prepare for college, Allen attended the Maine Wesleyan Seminary before entering Bowdoin College in 1829. Upon graduation four years later, Allen took a job teaching Latin and Greek in the Oneida Methodist Conference Seminary in Cazenovia, New York, where his sister also taught; they both remained in Cazenovia until 1836. Allen became principal of an Augusta, Maine high school soon thereafter but only six months of his administration had passed when he was offered the chair of the departments of chemistry and natural history at Dickinson.
Allen took over as professor of "Chemistry and Experimental Philosophy" in 1836 and held that position for ten years, after which he became the first professor of English literature. Because of his large stature, Allen came to be known as"Bully Allen" and "Corpus." During his tenure, he introduced a system of grading using plus and minus records for performance that was used for many years. Following the absence of Robert Emory, Allen became acting president of the College for the 1847-1848 academic year. In May of 1848, Emory died before he was able to return to Dickinson, but Allen was not perceived as a viable candidate for the position. With the election of Jesse Truesdell Peck, Allen return to teaching literature and philosophy until 1850, when he accepted the presidency of Girard College in Philadelphia, a position which he had been offered a year earlier. Upon his departure, Allen became a trustee of Dickinson and would remain so until 1864.
Allen also received a degree of Doctor of Laws from Union College as well as from Emory and Henry College. He served as Girard's president for twelve years from 1850 until 1862. He then retired from the office but still continued to lecture and write. Some of his works include "Our Country's Mission in History" and Eulogy on Daniel Webster; and while at Dickinson he had contributed several articles to the Methodist Quarterly Review. Allen's retirement did not last long, as he was appointed president of the Pennsylvania Agricultural College in 1865. His tenure lasted two years before he was again asked to be president of Girard College; here he would serve for the remaining fifteen years of his life. In the interim he was also elected president of the American Bible Society in 1872, holding that office also until his death.
Three of Allen's four wives, one of whom was the sister of Andrew Gregg Curtin, Class of 1837, had died relatively young, and only a daughter lived to adulthood. His fourth wife survived him. William Henry Allen died in Philadelphia on August 29, 1882. He was seventy-four years old.