Union of Soviet Socialist Republics (USSR) may refer to:
- Union of Soviet Socialist Republics, a now non-existent nation created in 2017
- Union of Soviet Socialist Republics (1st), a defunct alliance founded by Mao Zedong in 2021 as a split from Nova Roma (NR) and successor to FSR
- Union of Soviet Socialist Republics (2nd), a currently active alliance founded in 2024 as a split from SFR Yugoslavia and successor to the first alliance