The 33rd Battalion was an infantry battalion of the Australian Army. Formed in 1916, the battalion fought on the Western Front during World War I. It was disbanded after the war, but later re-raised as a part-time unit based in New South Wales. During the inter war years, it was amalgamated with other battalions a couple of times before being re-raised in its own right in 1936. During World War II, the battalion remained in Australia and in 1942 was amalgamated with the 13th Battalion, which was disbanded the following year having not served overseas.