Kazuo Hatoyama (鳩山 和夫 Hatoyama Kazuo?, May 6, 1856 – October 3, 1911) was the patriarchal head of the prominent Japanese Hatoyama political family which has been called "Japan's Kennedy family."
Kazuo was a graduate of Columbia University and Yale University Law School.
His wife, Haruko Hatoyama, was a co-founder of what is known today as Kyoritsu Women's University. His son is former Prime Minister Ichirō Hatoyama, who founded and was the first president of the Liberal Democratic Party (LDP). His grandson was former Foreign Minister Iichirō Hatoyama. His younger great-grandson Kunio Hatoyama served as Minister of Internal Affairs and Communications under Prime Minister Taro Aso until June 12, 2009. His older great-grandson Yukio Hatoyama is the leader of the Democratic Party of Japan (DPJ) and represents the 9th district of Hokkaidō in the House of Representatives. Yukio became Prime Minister on September 16, 2009, following a win by the opposition coalition in the 2009 elections.