Dionysius Lardner FRS FRSE (3 April 1793 – 29 April 1859) was an Irish scientific writer who popularised science and technology, and edited the 133-volume Cabinet Cyclopædia.

He was born in Dublin on 3 April 1793 the son of William Lardner and his wife; his father was a solicitor in Dublin, who wished his son to follow the same calling. After some years of uncongenial desk work, Lardner entered Trinity College, Dublin, in 1812. He obtained a B.A. in 1817 and an M.A. in 1819, winning many prizes.