Gerlach I

Gerlach I may refer to:


 * Gerlach I, Count of Nassau (before 1288 – 1361)
 * Gerlach I of Isenburg-Wied, Count of Isenburg-Wied from 1409 until 1413
 * Gerlach I of Isenburg-Arnfels (died 1303), Count of Isenburg-Arnfels from 1286 (1287) until 1303