The Bücker Bü 133 Jungmeister was an advanced trainer of the Luftwaffe in the 1930s. It was a single-engine, single-seat biplane of wood and tubular steel construction and covered in fabric.

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The Bü 133 was a development of the Bücker Bü 131 Jungmann two-seat basic trainer. First flown in 1935 by Luise Hoffmann, the first female works pilot in Germany, it was slightly smaller than the Bü 131. The prototype, D-EVEO, was powered by a 140 hp (104 kW) Hirth HM506 inverted, air-cooled inline-6 engine.

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The aircraft showed "astonishing agility" at its first public appearance, the 1936 International Aerobatic Championship at Rangsdorf, but the Bü 133A garnered no orders; only two Bü 133Bs, with 160 hp (119 kW) version of that same Hirth HM506 inline-6 engine, were built.

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The main production type was the 160 hp (119 kW) Siemens-Bramo Sh 14A radial powered Bü 133C, which had a distinctive cowling and a 13 cm (5.1 in)-shorter fuselage, and the same fine aerobatic performance as the Bü 133A.

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Fifty-two were manufactured under licence by Dornier for the Swiss Air Force (which kept it in service until 1968). A similar number were built for the Spanish Air Force by CASA, and were designated the CASA 1-133.