Nicholas Callan (20 December 1799 – 14 January 1864), an Irish physicist, invented the induction coil in 1836. Callan was a Roman Catholic priest and the professor of natural philosophy at St Patrick's College, Maynooth, from 1826 until his death. His work on electromagnets from 1836 to 1838 was based on that of William Sturgeon and Joseph Henry. He was slow to claim credit for his induction coil and the invention is often attributed to Heinrich Ruhmkorff (1857). In 1853 he received patent number 2340 for a rust-proofing treatment for cast iron, and in 1863 he invented the point plate rectifier. Many of Father Callan's original induction coils are displayed in the University museum.

The Callan Building on the north campus of NUI Maynooth, a university which was part of St Patrick's College until 1997, was named in his honour.

• Electricity and Galvanism (introductory textbook), 1832

Nicholas Callan at the Science Museum, Maynooth

• O'Hara, James G.Callan, Nicholas Joseph (1799–1864), Oxford Dictionary of National Biography, Oxford University Press, 2004
• Biography at corrosion-doctors.org