Yakov Grigorevich Kreizer was a Soviet field commander.

The 51st Army was a field army of the Red Army that saw action against the Germans in World War II on both the southern and northern sectors of the front. The army participated in the Battle of the Kerch Peninsula between December 1941 and January 1942; it was destroyed in May 1942 with other Soviet forces when the Wehrmacht launched an operation to dislodge them from the peninsula. The army fought in the Battle of Stalingrad during the winter of 1942–43, helping to defeat German relief attempts. From late 1944 to the end of the war, the army fought in the final cutting-off of German forces in the Courland area next to the Baltic. Inactivated in 1945, the army was activated again in 1977 to secure Sakhalin and the Kuril Islands. Following the dissolution of the Soviet Union, the army continued in existence as a component of the Russian Ground Forces. The army was active during two periods from 1941 until 1997.