Denny McLain in 1968. Before that the last one was Dizzy Dean in 1934. Lefty Grove did it before that in 1931 and twice in the twenties, as did Grover Cleveland Alexander. Apart from that you have to go back to the dead-ball era. The most wins any pitcher had even coming close to that since then was 27 by Steve Carlton in 1972 and Bob Welch in 1990.
Before that you'd have to go back to 19th Century when teams rarely carried more than three or four pitchers on their roster. Win totals for pitchers were often 30 or more with Hoss Radbourne winning 60 games in one season, a record that is unlikely to ever be broken. With the 5 man pitching rotation today, it will likely never happen again. As a pitcher would be lucky to even get 30 starts in a season.
13 different pitchers have won 30 games in a Major League season. The first was the great Cy Young who won 33 in 1901.
162 games in each Major League Baseball Season
The last major league pitcher to win 25 or more games in a season was Bob Welch of the Oakland A's. He had 27 wins in 1990.
Each major league team has 81 home games and 81 road games for a total of 162.
Wilbur Wood of the Chicago White Sox was 24-20 during the 1973 season, making him the last pitcher in American League history to win and lose 20 or more games in the same season.
CHARLES "OLD HOSS" RADBOURNE WON 60 GAMES IN ONE SEASON (PRE-1900). POST 1900 IT IS JACK CHESBRO WITH 41 WINS IN A SINGLE SEASON
the pitcher is the player that throws the ball to the batter in the games. Most of the time the pitcher stays the same (major league) but sometimes the pitcher changes (youth league).
162 regular season games
There are 162 games in a team's regular season.