British political, religious, and social reformer who championed humanitarian and constitutional causes far in advance of his time.

Educated at Trinity College, Dublin, and Peterhouse, Cambridge, he was ordained in 1763 and thereafter lectured on mathematics at Cambridge. His lectures on the Greek New Testament, begun in 1768, became controversial when he developed Unitarian views. His religious differences subsequently broadened to include opposition to mandatory clerical and university subscription to the Thirty-nine Articles and the Anglican liturgy and support for rational religion and religious toleration. His proposals in 1773–74 for annual public examinations of undergraduates were narrowly rejected at Cambridge. Following the resignation of his ecclesiastical livings on conscientious grounds in 1775, Jebb studied medicine, receiving the M.D. from St. Andrews and membership in the London College of Physicians in 1777.

In politics Jebb advocated a reform program that embraced universal suffrage, the secret ballot, equal single-member constituencies, and salaries but no property qualifications for members of Parliament. He began working actively for political reform in 1779, joining the Westminster Committee and helping establish the Society for Constitutional Information in 1780. His concern for prison reform is reflected in his Thoughts on the Construction and Polity of Prisons (1786). Jebb also championed the use of juries in libel cases, female equality, and medical education for laymen.