Leonard Lyell, 1st Baron Lyell, Bt (21 October 1850 – 18 September 1926), was a Scottish Liberal politician.
The eldest son of Colonel Henry Lyell and Katharine Murray Lyell, he was a nephew of Sir Charles Lyell, 1st Baronet, the geologist.
He served as Liberal Member of Parliament for Orkney and Shetland from 1885 to 1900, and was commissioned a Deputy Lieutenant for Forfarshire in December 1901.He was created a baronet in 1894 and raised to the peerage as Baron Lyell of Kinnordy in the County of Forfar, on 8 July 1914.He married Mary Stirling in 1874, and had one son, Charles Henry (1875-1918) and two daughters, Mary Leonora (Nora), born 1877, and Helen (Nelly), born 1878.
His only son Charles Henry Lyell was also a Liberal MP but as he died in 1918 his son Charles Anthony Lyell succeeded to both the baronetcy and barony.