Lyndon Earl "Mike" Welday (December 13, 1878 – May 28, 1942) was a left-handed Major League Baseball outfielder who played for the Chicago White Sox in 1907 and 1909.
He spent 24 games with the White Sox that season, batting .229 in 35 at-bats.
On August 18, 1909, he was sent by the White Sox to a minor league team to complete a deal made on July 9, 1909.
The White Sox sent players to be named later to the Providence Grays for Lena Blackburne.
[1] Welday also spent 10 (non-consecutive) seasons playing in the minor leagues, from 1901 to 1915.