Nesbitt, William (1824–81), professor of Latin and of Greek, was born in January 1824 in Co. Armagh, son of John Nesbitt (d. 1858), methodist minister (whose family moved with him to various congregations), and his wife, who may have been Jane Douglass. Nesbitt was educated mostly by his father, and was a pupil-teacher for a year in Raphoe Royal School. He entered TCD as a sizar on 17 June 1840. Despite having to take pupils to make money to pay for his own tuition, he had a brilliant undergraduate career, winning the classical scholarship in 1843 and graduating BA in 1845. He was awarded the first Berkeley gold medal in classics. He studied divinity, but did not take orders. Instead he taught in Dublin, and took his MA in 1848. The following year he became professor of Latin in QCG. In 1854 he resigned that chair to become professor of Greek in the same college, and in 1864 succeeded Charles Parsons Reichel as professor of Latin in QCB, where he stayed for the rest of his career. In 1880 his income was augmented when he was appointed college librarian; he was active in college administration, as well as in affairs in convocation.
Nesbitt's enthusiasm for education derived from his own experience of what it could do to enrich life. He had a particular interest in the social sciences, then becoming of increasing importance in intellectual life; it was Nesbitt's enthusiasm that led his close friend John Elliot Cairnes (qv) to devote himself to the study of political economy. An honorary doctorate of letters awarded at the last conferring of the QUI (October 1881) recognised Nesbitt's contributions to contemporary educational debates, as well as his inspiring teaching methods; he published little on classics. His pamphlets include three written in the 1860s on the Irish university question; he strongly supported the principle of non-denominational education, and was an influence on the development of state secondary education and in particular on the intermediate education act of 1878. Nesbitt supported women's efforts to obtain higher education, and worked with others first in founding the Ladies’ Institute in Belfast, where he gave lectures, and later in facilitating the admission of women students to the examinations of the RUI. He died 26 November 1881 in Mount Charles, Belfast, and was buried in Holywood, Co. Down.
Nesbitt married a daughter of George Minto Alexander, a judge in India; it is not known whether they had children. Her sister later married John Elliott Cairnes.