Sir Frederick Robert St John was a British diplomat.
- Occupation
- diplomat
- Position held
- ambassador of the United Kingdom to Serbia, ambassador of the United Kingdom to Switzerland, ambassador of the United Kingdom to Colombia, ambassador of the United Kingdom to Venezuela
- Citizenship
- United Kingdom of Great Britain and Ireland
- Born
- March 2, 1831, 1831
- Died
- February 27, 1923, 1923