Hugo Münsterberg was a German-American psychologist. He was one of the pioneers in applied psychology, extending his research and theories to industrial/organizational (I/O), legal, medical, clinical, educational and business settings. Münsterberg experienced immense turmoil with the outbreak of the First World War. Torn between his loyalty to the United States and his homeland, he often defended Germany's actions, attracting highly contrasting reactions.
Hugo Raudsepp was an influential and prolific Estonian playwright and politician. In 1951 he was deported to the Irkutsk region by the Soviet authorities, where he died.
Hugo Reid, a Scottish immigrant, was an early resident of Los Angeles County who became known for writing a series of newspaper articles, or "letters," that described the culture, language, and contemporary circumstances of the local Tongva (Gabrieleño) people. He criticized the Franciscan missionaries, who administered the Spanish missions in California, for their treatment of the native peoples.
Hugo Hermann Fürchtegott Treffner was the founder and first director of the Hugo Treffner Gymnasium in Tartu, and an important figure in the Estonian national awakening.
Hugo von Tschudi (1851–1911) was an art historian and museum curator. He was director of the Nationalgalerie in Berlin (1896–1909) where he acquired many important Impressionist works. Tschudi was born in Austria and became a naturalised Swiss citizen.