Ralph Pierre "Pete" LaCock, Jr. (born January 17, 1952) is a former Major League Baseball first baseman/outfielder. He batted and threw left-handed. In 1975, he hit the only grand slam of his career, in the final appearance by St. Louis Cardinals pitcher Bob Gibson.

LaCock was drafted by the Chicago Cubs in the first round (20th pick) of the 1970 January Draft-Regular Phase. His minor league career included leading the Texas League with 84 bases on balls while playing for the San Antonio Missions in 1971 and with 13 triples and 93 bases on balls while playing for the Midland Cubs in 1972.

Due to LaCock's success in the minor league system, he was accepted to the major leagues, where he played for the Cubs (1972–1976) and the Kansas City Royals (1977–1980). In 1981, he played in Japan for the Yokohama Taiyo Whales.

In nine seasons (715 games), he hit 27 home runs with 224 RBI and a batting average of .257. He was a good fielder at both first base and in the outfield, but never became an everyday player. He was often used as a pinch hitter and/or defensive replacement, and sometimes as a designated hitter. He was granted free agency on October 24, 1980, though he never played another major league game.

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