Carl Leonard "Lundy" Lundgren (February 16, 1880 – August 21, 1934) was an American baseball and football player and coach.

Lundgren played football and baseball for the University of Illinois Urbana–Champaign and played eight seasons of Major League Baseball as a pitcher for the Chicago Cubs. In eight years with the Cubs, he compiled a record of 91 wins and 55 losses. His best season was 1907 when he won 18 games, pitched 207 innings without allowing a home run, threw seven shutouts, and gave up only 27 earned runs in 28 games. His 1.17 earned run average was the second lowest in the major leagues, and his average of 5.652 hits allowed per nine innings was the lowest in the major leagues.

Control problems held him back from greater renown. The Atlanta Constitution in 1913 summarized Lundgren's strengths and weaknesses: "He had everything including speed to burn green hickory and an assortment of curves that would keep a criptograph specialist figuring all night but he was wild as a March hare in a cyclone and couldn't locate the plate with a field glass."

After retiring as a player, Lundgren became a coach. He was the head baseball coach and assistant football coach at the University of Michigan from 1914 to 1921. He was the head baseball coach and assistant athletic director at the University of Illinois from 1921 until his death in 1934. Lundgren's baseball teams at Michigan and Illinois won eight Big Ten Conference baseball championships, a total exceeded by only three other coaches in Big Ten history.

Lundgren was born in Marengo, Illinois in 1880. His father, Pehr Hjalmar Lundgren, was born in Östergötland, Sweden, emigrated to the United States in 1868 and worked as a house painter, contractor and interior decorator. His mother, Delilah (Renwick) Lundgren, was born on a farm outside Marengo. His father purchased a farm north of Marengo, where the family lived until 1900. Lundgren graduated from Marengo High School in 1898. He was the oldest of four children, having a younger brother, Franz Emil, and two younger sisters, Eva and Alma.

Lundgren enrolled at the University of Illinois Urbana–Champaign in 1898, studied civil engineering, and graduated in 1902. As a senior, he published a paper titled, "Comparative strength of gravel and broken-stone concretes". While at Illinois, he played at the halfback and fullback positions for the Illini football team for three years. He was also a pitcher for the Illini baseball team from 1899 to 1902 and was the team captain in 1902.

The Chicago Cubs saw Lundgren pitch in an exhibition game between the Illinois college team and the Cubs. The Cubs gave Lundgren a tryout, and he made his major league debut for the Cubs on June 19, 1902, shortly after completing his studies at the University of Illinois. One sports writer noted that "the Cubs had a new pitcher, and the world lost a civil engineer." In his rookie season, Lundgren pitched 17 complete games (in 18 appearances) and had an earned run average of 1.97.

Lundgren pitched for the Cubs from 1902 to 1909 and compiled a 91–55 (.623) record and career earned run average of 2.42. During his best years, from 1904 to 1907, he compiled a record of 65–27. The Cubs won three straight pennants in 1906, 1907, and 1908 and World Series championships in 1907 and 1908. During the 1906 and 1907 seasons, Lundgren compiled records of 17–6 and 18–7.