John Borland Thayer II (April 21, 1862 – April 15, 1912) was an American businessman who had a thirty-year career as an executive with the Pennsylvania Railroad Company.
He was a director and second vice-president of the company when he died a week before his 50th birthday in the sinking of the RMS Titanic, on April 15, 1912.
In his youth, Thayer was also a prominent sportsman, playing baseball and lacrosse for the University of Pennsylvania and first-class cricket for the Philadelphian cricket team.
He is the only first-class cricketer known to have died aboard Titanic.