The pitcher that struck out the most batters in history is Nolan Ryan. He has struck out 5,714 batters during his career from September 11, 1966 until September 22, 1993.
The record occurred during the period 1884 to 1886. The American Association and the Union Association of that time are both considered to be a major league. In 1886, Matt Kilroy struck out 513 batters. In 1884, Hugh Daily struck out 483. "Old Hoss" Radbourne struck out 441 in 1884 for a National League team. Since 1886, the most strike-outs in a season by a pitcher was 383 by Nolan Ryan in 1973.
There have been 51 instances in which a pitcher has struck out four batters in one half inning. The most recent was Scott Shields of the Los Angeles Angels on June 21, 2008.
Roger Clemens with 20 struck out batters! XD
Nolan Ryan struck out the most batters, but Reggie Jackson struck out the most at the plate.
Mark buerle 45
As of the 2010 season, the Yankees team record for strikeouts by a pitcher in a season is 248 by Ron Guidry in 1978.
In the minor leagues that was Ron Necciai of the 1952 Bristol Twins who struck out 27 batters in a no-hitter against the Welsh Miners in an Appalachian League game. In MLB that was Nolan Ryan of the 1973 California Angels who struck out 17 batters in a no hitter against the Detroit Tigers.