Gerlach I of Lower Isenburg (German: Gerlach I. von Nieder-Isenburg) was the Count of Lower Isenburg from 1458 until 1490. From 1486 Gerlach I reigned with James. In 1460 Gerlach purchased the Lowership of Grenzau from the Archbishopric of Trier.

Preceded by:

Gerlach I

Succeeded by:

Salentin V Count of Lower Isenburg
1458 - 1490
with... James
1486 - 1490
James and Gerlach II