CB may refer to
- Casus belli, a Latin expression meaning justification for an act of war.
- The First and Second Celestial Beings, multi-colored team alliances, the first of which eventually merged into the Random Insanity Alliance, and the second which currently exists.
- The Crimson Blades, a defunct micro-alliance best known for the Legion-Crimson Blades War.
- The First and Second Crimson Brigades, Black team micro alliances which merged to form Another Alliance in February 2009 and the Crimson Auric Legion in October 2009 respectively.