The Tombigbee darter (Etheostoma lachneri) is a species of darter endemic to the eastern United States, where it occurs in the Tombigbee River system in northeastern Mississippi and Alabama. It inhabits sand- and rock-bottomed pools of headwaters, creeks, and small rivers, and small streams with mixed sand-gravel substrate, and creeks with mixed sand, gravel, and hard clay or bedrock substrate.