Isaiah Leo 'Si' Kenen (1905-1988) was a Canadian-born American lawyer, journalist, Zionist activist, and lobbyist who played a pivotal role in advancing U.S. support for Israel. Born on March 7, 1905, in Ottawa, Ontario, Canada, to Jewish immigrant parents from Eastern Europe, he grew up in a family immersed in Zionist ideals. He earned a Bachelor of Arts from the University of Toronto in 1925 and a Bachelor of Laws from Osgoode Hall Law School in 1928. After briefly practicing law in Canada, he moved to the United States in 1929, became a naturalized citizen, and established himself as a journalist writing for Jewish publications covering international affairs related to Jewish and Zionist causes. In 1951, he founded the American Zionist Council (AZC) as a precursor to AIPAC. To address scrutiny over foreign funding allegations, he established the American Zionist Committee for Public Affairs (AZCPA) in 1954, later renamed the American Israel Public Affairs Committee (AIPAC) in 1959, serving as its executive director until 1974. Under his leadership, AIPAC grew into a powerful bipartisan lobbying group focused on influencing U.S. foreign policy through educational and public affairs work without direct foreign agent registration. His strategies included building relationships with Congress and media, drawing on his journalistic background to shape narratives around Israel's security needs. Throughout his life, he was recognized for his advocacy, though his work occasionally drew controversy, including investigations by the Department of Justice in the 1960s regarding AIPAC's funding sources. He authored books like 'Israel's Defense Line' (1969) and continued writing columns for the Near East Report until his retirement. He passed away on March 23, 1988, in Washington, D.C., leaving a lasting legacy as the architect of one of the most influential pro-Israel lobbies in the United States.