Katzelsdorf-Schloss, Protected medieval castle in Katzelsdorf, Austria.

Katzelsdorf Castle consists of three residential wings arranged in a horseshoe around a courtyard, about 2 km south of Wiener Neustadt in Lower Austria. Two-storey Baroque arcades with groin vaults line the courtyard, glazed during the last restoration, and the south side is closed by a gate. Remains of frescoes from the original construction survive under the plaster of the east wing, and Renaissance graffiti are visible in the north corner of the west wing.

The first castle was built in the 12th century; the village of Katzelsdorf appears in Salzburg documents in 1183, though a castle there is not confirmed for that date. In 1635 the Koenigsberger family built or enlarged the fortified castle, completed five years later. After the family died out, the estate passed to Johann Baptist Menshengen, who sold it to the Hoyos family in 1773.

From the early 19th century the castle and the Frohsdorf estate shared the same owners. Around 1822–1830 it belonged to Countess Karolina Lipona, Caroline Bonaparte, Napoleon's youngest sister. By 1844 the Duchess of Angoulême, Marie Thérèse Charlotte de Bourbon, daughter of Marie Antoinette, held it, after the dukes of Blacas d'Aulps.

The castle stands in the southern part of Katzelsdorf, about 2 km south of Wiener Neustadt, surrounded by its park. The three residential wings form a horseshoe around a courtyard with two-storey baroque arcades; the south side is closed by a gate. The upper floor of the east wing was converted into a ballroom with an open roof structure in 1997.

During World War II the castle housed the largest horse hospital on the Eastern Front. Military forces occupied the main building and used it to treat horses during the campaigns.