Vilyelmo Rumanovich Dumayev (Margovyan: Guillermo Rumano Dumayo, Russian: Вилельмо Руманович Думаев, also known as William Do, 2 November 1972 - 17 April 2013) was a Margovyan politician and later on political terrorist. He was a senator and Senate President. Dumayev officially became the 16th President of the Senate of Margovya after winning the majority conclave on May 19, 2004 following the death of Senate President Iosef Dimakulanov. Dumayev won against Senator Irina Adzhitekova with a score of 20 against 10.
After placing thirty-eighth on the September 2005 senatorial elections, Dumayev started rebelling against the government and later on became a political terrorist, attacking and assassinating politicians. Dumayev died on April 17, 2013 in Margovya City, Arbatskaya, after an encounter with former President Gennady Elemat.