Streltsy (Russian: стрельцы́, streltsý, literally "shooters"; sg. стреле́ц, streléts, "shooter", from strelyat' , "to shoot") were the units of Russian guardsmen from the 16th to the early 18th centuries, armed with firearms. They are also collectively known as Marksman Troops (стрелецкое войско). These standing forces reinforced the mounted nobility militia (поместное войско, pomestnoe vojsko or Landed Army) mobilized during wartime.
The first streltsy units were created by Ivan the Terrible sometime between 1545 and 1550 and armed with arquebuses. During his reign, Russia was fighting wars almost continuously, including the Livonian War in the North and wars against the Khanates in the South. They first saw combat at the Siege of Kazan in 1552. Initially, the streltsy were recruited from among the free tradespeople and from the rural population. Subsequently, military service in this unit became lifelong and hereditary. Thus, while earlier in the 16th century they had been an elite force, their effectiveness was reduced by poor training and lack of choice in recruiting.
Streltsy were subdivided into vyborniye (выборные), or electives (later – of Moscow) and gorodskiye (городские), or municipal (in different Russian cities).
Streltsy came under the control of the Streltsy Department (Стрелецкий приказ, or Streletsky prikaz); however, in times of war they came under their superiors. The municipal streltsy were also under the jurisdiction of the local voevodes.