Hanna, Samuel (1771–1852), presbyterian minister and professor, was born at Kellswater, Co. Antrim, fifth son of Robert Hanna of Kellswater, who may have been a farmer, or in trade, or both. His mother's name is not known. In 1789 he graduated MA from the University of Glasgow, and in 1795 was ordained a presbyterian minister in the congregation of Drumbo, Co. Down. The young man ministered successfully there for four years, then in 1799 accepted a call to Rosemary St., Belfast, one of the oldest churches in the city. The congregation was somewhat divided and demoralised after the imprisonment of Hanna's predecessor Sinclair Kelburn (qv), who had supported the United Irishmen in the 1798 rebellion, but it soon grew in numbers and enthusiasm under Hanna's guidance. He preached three and even four times on Sundays, and the church was first extended (1803) and then completely rebuilt (1830–31) to hold more members. In 1817, in a development that was seen as expressive of the church's opposition to government attempts to regulate the education of presbyterian ministers, Hanna was chosen by the synod of Ulster as the first professor of theology to teach intending ministers in the Belfast Academical Institution. He also taught some church history. He had about twenty students each session, who also often attended his church, so his views and practices were very influential in nineteenth-century Ulster presbyterianism, as increasingly students stayed in Ulster for their education, rather than going to Scottish universities.
A competent rather than inspiring teacher, he was nicknamed ‘Old Fadge’ by his students which suggests that his lectures reminded them of the sustaining but solid regional speciality, potato bread. He was awarded the degree of DD (1818) by Glasgow. Hanna worked for the cause of missions, for Sunday schools, and for efforts to provide Bibles for Ireland's poor; he was moderator of synod in 1809–10, and produced a book of hymns in the 1820s (a very early date in the history of that genre), which was apparently intended only for children among his own congregation. He is remembered chiefly, however, as the first moderator of the Presbyterian Church in Ireland, which was created when the synod of Ulster united with the secession synod (7 July 1840). This was a most important moment in the history of the denomination, and brought to an end years of controversy. Members of both synods went in procession from their separate meetinghouses to unite in Rosemary St. church, and Hanna formally constituted the church court of the new body. The distinction thus conferred on Hanna indicates the respect in which he was held, though by 1840 he was in failing health and had asked his congregation to appoint an assistant: William Gibson (qv) was chosen. From that year also, he shared the chair of theology with Samuel Edgar (qv). On Hanna's death the faculty's government grant was reduced by £250.
Hanna married (1800) Martha (d. 1860), daughter of Robert Gemmill, a muslin manufacturer, originally from Scotland. On 23 April 1852 Samuel Hanna died at the home of his daughter Eliza and son-in-law James Denham, a presbyterian minister in Londonderry. He was buried a week later in the New Burying Ground, Belfast.