Oemar Said Tjokroaminoto

Tjokroaminoto was born the second of twelve children, in the Ponorogo Regency as the son of RM. Tjokroaminoto (district chief of Kleco), grandson of RMA. Tjokronegoro (regent of the Ponorogo Regency), and great-grandson of Kyai Bagus Kasan Besari of Tegalsari pesantren. According to his genealogy, his education was directed towards civil service.

After graduating in 1902 from OSVIA (Dutch: Opleiding School Voor Inlandsche Ambtenaren), a school for indigenous civil servants, in Magelang, the then-highest civil servant education institution, he worked as one in Ngawi for three years from 1902 to 1905). He moved to Surabaya, where he met Samanhudi, founder and leader of the Islamic Trade Unions (SDI). At night, he attended Burgerlijke Avond School (BAS) for some years. After graduating, he worked in a sugar refinery (1907–1912). He wrote for the Bintang Soerabaja (Surabaya Star) daily and became a staff assistant.

Known as the "Crownless King of Java" (Dutch: De Ongekroonde van Java) by the Dutch, Tjokroaminoto was one of the pioneers of the trade union movement in Indonesia and was a teacher of some of the most well-known leaders of Indonesia. His political ideas also gave birth to various ideologies of Indonesia at that time, when he tutored students in his household, such as Semaoen, Alimin, Musso, Sukarno, Kartosuwiryo, and even Tan Malaka. He was the first to refuse to submit to the Netherlands. After he died, the colors of the Indonesian movement were developed by his students, the socialists and communists embraced by Semaoen, Musso, and Alimin.

One of his most famous quotes was "Highest education, purest tauhid, smartest of strategies" (Indonesian: Setinggi-tinggi ilmu, semurni-murni tauhid, sepintar-pintar siasat), depicting the atmosphere of Indonesian struggle in its time which required the three aforementioned abilities of a freedom fighter. Of the various students he liked most was Sukarno until he married Sukarno with his daughter Siti Oetari, Sukarno's first wife. His message to his disciples was "If you want to be a great Leader, write like a journalist and talk like an orator". These words influenced his disciples to make Sukarno shout every night to learn the speeches to make his friends, Musso, Alimin, SM Kartosuwiryo, Darsono, and others wake up and laugh to watch it.