8661 Ratzinger (1990 TA13) is a main-belt asteroid discovered on October 14, 1990 by Lutz D. Schmadel and Freimut Börngen at Tautenburg. The asteroid was named after then Cardinal Joseph Ratzinger (who later became Pope Benedict XVI) for the role he played in supervising the opening of Vatican archives in 1998 to researchers investigating judicial errors against Galileo and other medieval scientists. The name was proposed by the asteroid's first discoverers.