"Tommy Atkins," or "Tommy," is one common nickname for British soldiers. The term is associated with World War I in particular, but was used as early as the 18th century.
During World War I, French and Commonwealth troops referred to British soldiers as "Tommies." German soldiers would shout “Tommy” across the trenches to get the attention of a British soldier. Use of the term declined in subsequent decades, although “Tom” is sometimes still heard in reference to paratroopers.
The origin of the nickname is uncertain. A letter from Jamaica in 1743, which was about a troop mutiny, refers to Tommy Atkins. Another theory says that the original Tommy Atkins was a British solider in the American Revolutionary War. A further explanation holds that the term came into common use when the War Office chose “Tommy Atkins” as a generic name in 1815.