Hanserd Knollys (1599–1691) was an English particular Baptist minister.
He was born at Cawkwell, Lincolnshire, about 1599. He was educated privately under a tutor, was for a short time at Great Grimsby grammar school, and afterwards matriculated at St Catharine's College, Cambridge in 1627 or 1629. Leaving the university, he became master of the grammar school at Gainsborough, Lincolnshire. In 1620 he was ordained (29 June, deacon; 30 June, priest), and he was presented to the vicarage of Humberston, Lincolnshire, by John Williams, at that time bishop of Lincoln. He preached also every Sunday in the neighbouring churches of Holton-le-Clay and Scartho, but in two or three years resigned his living owing to scruples about ceremonies and admission to the communion, continuing, however, to preach. By 1636 he had become a separatist, and renounced his orders. He removed to London with his wife and family, and shortly afterwards fled to New England to escape the high commission court. A warrant from that court reached him at Boston, but after a brief imprisonment he was allowed to remain unmolested. He preached at Dover, New Hampshire. Cotton Mather enumerated him among 'godly anabaptists;' quite when he adopted doctrine and practice to justify the comment is not clear.
On 24 December 1641 he reached London on his return, which was for his aged father, He opened a boarding-school on Great Tower Hill. Soon afterwards he was elected to the mastership of the free school in the parish of St. Mary Axe. After about a year he gave it up to become an army chaplain; but dissatisfied with the parliamentary commanders, he returned to London and to school-keeping. He learned Hebrew from Christian Ravis of Berlin. In 1644 he preached in London and Suffolk churches and churchyards, and occasionally, in what afterwards became quaker fashion, endeavouring to supplement the regular sermon by a discourse of his own. This led, according to Thomas Edwards, to tumults. Knollys was twice brought before a committee of parliament, but on each occasion was absolved from blame and protected. In 1645, with Benjamin Cox and others, Knollys was the author of A Declaration concerning the Publicke Dispute which should have been in the Meeting House of Aldermanbury, December 3 1645, concerning Infant Baptism.