The following list is of the top 100 pitchers in career strikeouts in Major League Baseball. In baseball, a strikeout occurs when the batter receives three strikes during his time at bat. Strikeouts are associated with dominance on the part of the pitcher and failure on the part of the batter. Nolan Ryan has the most career strikeouts in Major League Baseball. During a record 27-year career, he struck out 5,714 batters. The American League record is held by Roger Clemens (4,167 strikeouts), while in the National League, the record is 4,000 by Steve Carlton.