List of Famous people born on April 21st

Robert Thoeren (1903–1957) was a German screenwriter and film actor. Thoeren was born in Moravia, then part of the Austro-Hungarian Empire. After the First World War the German-speaking Thoeren emigrated to Germany where he became a theatre and film actor. Thoeren appeared in leading roles in several German-language films made by Paramount at the Joinville Studios in Paris.

Boris Dmitrievich Grekov was a Russian Imperial and Soviet Russian historian noted for his comprehensive studies of Kievan Rus and the Golden Horde. He was a member of the Soviet Academy of Sciences (1934) and several foreign academies, as well as Director of the Russian History Institute in Moscow.

Shaquille Green Thompson is an American football outside linebacker for the Carolina Panthers of the National Football League (NFL). He played college football at Washington. He also had a short stint with the Boston Red Sox organization as part of their rookie team in the Gulf Coast League. Since being drafted, he has played a hybrid safety/linebacker position for the Panthers. He is regarded as their "big nickel" and covers mismatches in the pass or run game.

August Robert Zimmermann (1815–1864), a landscape painter, was born at Zittau. Among his pictures are The Innthal, near Kufstcin, and a Waterfall, both dated 1863. He died at Munich. He was the brother of painters Albert, Richard, and Max Zimmermann.