(1) John Herschel Glenn Jr., b. 1921, astronaut and US Senator from Ohio, who wrote the foreword for Fitness Over Fifty
(2) John Glenn, b. 1963, author of The Soviet legacy in Central Asia
(3) split and aliased for no reason
(4) John A. Glenn, author of A Dictionary of Mathematics
(5) John Glenn, Catalogue of the Francis Trigge Chained Library, St. Wulfram's Church, Grantham
(7) Glenn, John 1968- Civil Engineers!