Siebel originally Flugzeugbau Halle was a German aircraft manufacturer founded in 1937 in Halle an der Saale. It was revived as Siebelwerke in 1948. In 1952 it merged with ATG to form Siebelwerke-ATG Gmbh (SIAT). In 1968 SIAT was absorbed by Messerschmitt-Bölkow-Blohm.