| Year | Ruler | Party (from 1918 onwards) |
| 1871-1888 | |
| 1888 | |
| 1888-1918 | |
| 1918-1925 | |
| 1925-1934 | |
| 1934-1945 | |
| 1945 (disputed) | |
| 1949-1963 (West Germany) | |
| 1946-1950 (East Germany) | |
| 1950-1971 (East Germany) | |
| 1963-1966 (West Germany) | |
| | Year | Ruler | Party (from 1918 onwards) |
| 1966-1969 (West Germany) | |
| 1969-1974 (West Germany) | |
| 1971-1989 (East Germany) | |
| 1974-1982 (West Germany) | |
| 1982-1990 (West Germany) | |
| 1989 (East Germany) | |
| 1989-1990 (East Germany) | |
| 1990-1998 | |
| 1998-2005 | |
| 2005- | |
|