Major General Daniel Hermanus ("Dan") Pienaar was a South African World War II military commander. Pienaar joined the artillery branch of the Natal Police (NP) in 1911, and transferred to the Union Defence Forces (UDF) when they took over the NP in 1913. In World War I, he served as an artilleryman with the South African Overseas Expeditionary Force in German East Africa and Palestine. Between the two world wars, Pienaar held various staff and command posts.