Ichirō Hatoyama (鳩山 一郎, Hatoyama Ichirō; 1 January 1883 – 7 March 1959) was a Japanese politician who served as prime minister of Japan from 1954 to 1956. During his tenure he oversaw the formation of the Liberal Democratic Party (LDP) and restored official relations with the Soviet Union.
Hatoyama was born in Tokyo as the eldest son of politician Kazuo Hatoyama. After graduating from Tokyo Imperial University, he practiced law before entering political life, and was first elected to the Diet in 1915 as a member of the Rikken Seiyūkai. He served as chief cabinet secretary under Giichi Tanaka from 1927 to 1929, and minister of education under Tsuyoshi Inukai and Makoto Saitō from 1931 to 1934. He was one of the leading members of the Seiyukai prior to its dissolution in 1940, and during the Pacific War opposed the cabinet of Hideki Tōjō. In 1945, Hatoyama founded the Liberal Party, which became the largest party in the first post-war election, but he was purged by the American occupation authorities before taking office, and handed the post to Shigeru Yoshida. Hatoyama was de-purged in 1951, but his conflict with Yoshida over the leadership split the Liberal Party in two. Hatoyama then founded the Democratic Party in 1954.