Dennis Patrick Aloysius Lyons (March 12, 1866 – January 2, 1929) was an American Major League Baseball player.

In 1888, the Athletics had a winning season, and finished third in the standings, and for the second straight year, Lyons led the team in batting.

The team finished in eighth place and then jumped from the American Association to the ill-fated Players League.

In 1891, Lyons signed with the St. Louis Browns, a team managed by future owner of Chicago White Sox, Charles Comiskey.

Though his batting average dipped (Lyons only hit .257) he still maintained his power, tying with Buck Ewing for the most home runs on the team with 8.

He would become a manager and part time player for the Beaumont Oil Gushers of the class C South Texas League in 1903.

At the age of 40, Lyons would spend his last year in organized baseball as a manager of the Lake Charles Creoles, also a member of the class C South Texas league.