Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Louis Marcellus Nagelsen (June 29, 1887 - October 21, 1965) was a Major League Baseball catcher who played for one season. He played for the Cleveland Naps for two games during the 1912 Cleveland Naps season. Major League Baseball (MLB) is the highest level of professional baseball in the United States and Canada, consisting of teams that play in the National League and the American League. The two leagues merged in 2000 into a single MLB organization led by the Commissioner of Baseball after 100 years as separate legal entities.