Aviezri Siegmund Fraenkel (Hebrew: אביעזרי פרנקל; born June 7, 1929) is an Israeli mathematician who has made contributions to combinatorial game theory.

Aviezri Siegmund Fraenkel was born in Munich, Germany, to a Jewish family, which then moved to Switzerland soon thereafter.

One of his grandchildren, Yaacov Naftali Fraenkel, was kidnapped and murdered by Hamas members in June 2014.

In 2018, in respect for his life's work, Fraenkel was given the highly regarded honor to light one of twelve torches—one for each of Twelve Tribes—at the State of Israel's televised opening ceremony on Har Herzl, Jerusalem, in celebration of Israel's 70th Independence Day (which in 2018, fell on Wednesday evening April 18 – Thursday evening April 19).

Fraenkel was the founder of the Bar Ilan Responsa Project, serving as its initial director (1963–74), which received the Israel Prize in 2007.