John Robert "Jack" Monsell (15 August 1877 – 20 March 1952) was an Irish illustrator.
Monsell was born at Cahirciveen, County Kerry, to a wealthy Anglo-Irish family. His great uncles were Sir Aubrey de Vere and Sir Stephen de Vere. In 1902 the family moved to Chelsea.
He served as an officer in the British Army during the First World War
He married the novelist Margaret Irwin in 1927.
His edition of The Rose and the Ring by William Makepeace Thackery was largely successful.
His sister Elinor Monsell was also an illustrator.