Stepan Zorian (Armenian: Ստեփան Զորեան) better known by his nom de guerre Rosdom (Ռոստոմ), (1867-1919) was one of the three founders of the Armenian Revolutionary Federation along Christapor Mikaelian and Simon Zavarian, also part of Armenian national liberation movement.

Rosdom was born in the village Tzghna of Koghtni. He attended the Village Administration college of Moscow but dropped out before graduating. He eventually went to Tiflis, Georgia where he became an activist and revolutionary. There he met fellow revolutionaries Christapor Mikaelian and Simon Zavarian. Together, they co-founded the Armenian Revolutionary Federation (ARF) in 1890. Their new political party had a major impact on Armenians. It gained support by demanding reforms and taking up arms to defend Armenian citizens of the Ottoman Empire.

Rosdom eventually moved to Geneva, Switzerland where he managed the Troshag newspaper, as the editor. In Garin, pretending to be a teapot salesman because ARF party members were banned in Turkey, he established student unions.

He later settled in Bulgaria to create cooperation between ARF and the Macedonian Revolutionaries in their struggle against Abdul Hamid II. He also opened an Armenian school there with his wife, Lisa Melik Shahnazarian.

During the 1908 Constitutional revolution in Turkey, he moved to Garin. In 1914, World War I broke out, he moved to Europe and then to the Caucasus. There he participated in the Armenian-Tatar wars. During the Iranian revolution, he participated in the revolution alongside Persian revolutionaries. He also directs the fight of self-defense in Baku, Azerbaijan. After the disastrous results, he flees to Iran with thousands of Armenians.

Rosdom died in 1919, in the city of Tiflis at the age of 52. He is the only one of the three founders of the ARF to see an independent Armenia, which was the party's primary goal. The independence happened on May 28, 1918. Armenia's independence lasted only for two years before falling to the Soviets.