15. Socialist Unity Party (SED, East Germany)
The Socialist Unity Party of Germany (SED) ruled East Germany from 1946 until the fall of the Berlin Wall in 1989, enforcing a socialist regime under Soviet influence. (en.wikipedia.org) Its rapid demise after popular unrest marked the end of one-party dominance in the region. Some former SED politicians remain active in modern parties, but the SED is history. More at DW.
