Elmer "Sonny" Lim is a Hawaiian musician and slack key guitar player from Waimea (Kamuela) on the Big Island of Hawaii. Sonny is part of the musical Lim Family, which is also famous in the 50th State.

Sonny's father, Elmer Lim Sr., who was a Paniolo (Hawaiian cowboy) on the famed Parker ranch and later worked for the ranch himself. In this respect, Sonny carries on the slack key tradition born amongst Waimea Cowboys over a hundred years earlier. Like Ledward Kaapana, however, Sonny learned primarily from Kaapana's uncle, Kalapana slack key master Fred Punahoa, who moved in with Sonny's family for several weeks to teach him.