William B. Coster

William Bay Coster (1867 – December 19, 1918) was an American banker who was prominent in New York Society during the Gilded Age. Early life Coster was born in New York and lived at a large home at 103 East 71st Street. He was one of four children born to Charles Robert Coster (1839–1888) and Marie Bay (née James) Coster (1841–1904), who were married in 1864. Among his siblings was brother Charles Coster, and sister Elizabeth Mary Coster, who married Alfred Egmont Schermerhorn. His father was a soldier and public official, who is best known for commanding a brigade at the Battle of Gettysburg. His maternal grandfather was Augustus J. James of Albany, the brother of theologian Henry James Sr., making William's mother Marie a first cousin of author Henry James, psychologist William James, and diarist Alice James. His paternal grandparents were John H. Coster and Sarah Adeline (née Boardman) Coster, making his father a first cousin of fellow New York clubman, Harry Coster. His great-grandfather, John Gerard Coster, came from Haarlem in the Netherlands to the United States shortly after the Revolutionary War and founded the family fortune through the mercantile firm, "Henry A. & John G. Coster". Career Coster became a stockbroker and opened up an office with his brother Charles and John M. Knapp in 1893. He later transferred his seat to Knapp in 1907, and resigned from the firm. He later became a partner in Morgan Drexel. He was known as a speed walker, who could be seen "traversing the sidewalks between the New York Athletic Club and the stock exchange in record time."