A lock cylinder includes a housing, in which a sleeve having a cylinder core accommodated therein is rotatably supported. The cylinder core has spring-loaded tumblers forming a form closure with recesses arranged in the sleeve when a key engaging the tumblers is removed. Inside the housing, the sleeve is coupled to a coupling element by means of a disengaging sleeve. The coupling element is supported inside the housing and connected to a bearing in a rotationally-fixed manner. The bearing supports an output element. At least one of the sleeve and the coupling element forms a form closure with the bearing to block the rotation of the output element if an improper object is used in operative connection with the cylinder core.