There is provided grommet and plate assemblies for sealing fiber optic closures into which and/or out of which fiber optic cables are routed. The grommet of the assembly includes a central portion with an axial opening adapted to receive the fiber optic cable through a slit in the central portion. The grommet also includes an end cap portion on an axial end of the grommet, and the end cap portion includes a deformable outer lip that overhangs an outer surface of the central portion to provide axial retention of the grommet once it is inserted into an opening of the plate. The plate includes a plurality of openings into which grommets may be selectively inserted. The plate may be received within an opening of the fiber optic closure and includes a slot for receiving a protrusion within the opening of the fiber optic closure.