A niche for a pool or spa light includes a back wall having an aperture for a power cable, a side wall, a plurality of mounting ribs, and a groove formed in at least one of the plurality of mounting ribs for receiving a locking mechanism of a pool or a spa light for locking the pool or spa light in position with respect to the niche. In another embodiment, a niche for a pool or spa light includes a body and a rotatable hub with a plurality of mounting ribs for attaching a pool or spa light to the hub. The body includes a back wall having a power cable aperture and a threaded aperture for receiving a screw, and a side wall. The hub includes a back wall having an aperture for receiving the screw and a plurality of mounting ribs, the hub being rotatable about the screw. A groove is formed in at least one of the plurality of mounting ribs for receiving a locking mechanism of a pool or a spa light for locking the pool or spa light in position with respect to the niche.