Isidore Gluckstein (1851–1920) was a director of Salmon & Gluckstein tobacco merchants, and one of the founders of J. Lyons and Co., a restaurant chain, food manufacturing, and hotel conglomerate created in 1884 that dominated British mass-catering in the first half of the twentieth century.
Isidore Gluckstein was the son of Samuel Gluckstein, the founder of Salmon & Gluckstein.
He married Rose Cohen (1851–1908). Among their children were:
Sir Samuel Gluckstein (1880–1958)
Lena Gluckstein, who married Harry Salmon
Major Montague Isidore Gluckstein OBE (1886–1958)