The origin of the nickname Big Ben is the subject of some debate. The nickname was applied first to the Great Bell; it may have been named after Sir Benjamin Hall, who oversaw the installation of the Great Bell, or after boxing’s English Heavyweight Champion Benjamin Caunt. Now Big Ben is often used, by extension, to refer to the clock, the tower and the bell collectively, although the nickname is not universally accepted as referring to the clock and tower. Some authors of works about the tower, clock and bell sidestep the issue by using the words Big Ben first in the title, then going on to clarify that the subject of the book is the clock and tower as well as the bell.  The official name of tower is Elizabeth Tower, named in tribute to Queen Elizabeth II in her Diamond Jubilee year in 2012. Source Wikipedia