Count Semyon Romanovich Vorontsov (or Woronzow, Russian: ????? ????????? ???????´?; 26 June 1744 – 9 July 1832) was a Russian diplomat from the aristocratic Russian Vorontsov family, whose siblings included Alexander Vorontsov, Elizaveta Vorontsova and Yekaterina Vorontsova-Dashkova.
He resided in Britain for the last 47 years of his life, from 1785 until his death in 1832, during which time he was the Russian ambassador to the Kingdom of Great Britain from 1785 to 1800 and to the United Kingdom from 1801 to 1806.