Barbados
noun: Barbadian(s) or Bajan (colloquial)
adjective: Barbadian or Bajan (colloquial)

Belarus
noun: Belarusian(s)
adjective: Belarusian

Belgium
noun: Belgian(s)
adjective: Belgian

Belize
noun: Belizean(s)
adjective: Belizean

Benin
noun: Beninese (singular and plural)
adjective: Beninese

Bermuda
noun: Bermudian(s)
adjective: Bermudian

Bhutan
noun: Bhutanese (singular and plural)
adjective: Bhutanese

Bolivia
noun: Bolivian(s)
adjective: Bolivian

Bosnia and Herzegovina
noun: Bosnian(s), Herzegovinian(s)
adjective: Bosnian, Herzegovinian

Botswana
noun: Motswana (singular), Batswana (plural)
adjective: Motswana (singular), Batswana (plural)