Magenis married firstly, 1788, Lady Elizabeth Anne Cole (died 26 May 1807), daughter of William Cole, 1st Earl of Enniskillen and niece of Hon. Arthur Cole-Hamilton, with whom he represented Enniskillen. They had five sons and four daughters.[3]
Richard William Magenis, his heir
William John Cole Magenis
Lieut.-Col. Henry Arthur Magenis (July 1795 – 11 June 1828) of the 87th Royal Irish Fusiliers
John Balfour Magenis (died 1862), married Frances Margaretta Moore, daughter of Judge Arthur Moore and Frances Stoney
Anne Louise Magenis (died 1855), married in 1821 David Albemarle Bertie Dewar
Elizabeth Anne Magenis (died 1882), married James Wilmot Williams, of Heringston, Dorset
Florence Sarah Magenis, died unmarried
Florence Catherine Magenis (died 1837), married in 1821 John Ashley Warre
Magenis married secondly, Elizabeth Callander, widow of Col. George Dashwood, and daughter of James Callander Campbell, of Craigforth, a claimant of the Campbell baronetcy. With her he had a sixth son:
Frederick Richard Magenis (1816–1866), died unmarried