A rotary damper has a displacer device with a damper shaft and displacer components engaging into one another. A rotational movement of the damper shaft can be damped. The displacer device contains a magnetorheological fluid as a working fluid. A magnetic field of a magnetic field source having an electric coil can be controlled by way of an associated control device. An end-side axial gap is formed between the housing and the displacer device. An essential part of the magnetic field of the magnetic field source passes through the axial gap between the housing and the displacer components. The magnetorheological fluid is subjected to the magnetic field in order to adjust a damping of the rotational movement of the damper shaft. The magnetic field also effects a seal of the end-side axial gap.