A reflector (1) for lighting devices comprises a main body (2) having a cavity (3) and a central axis (X-X); the main body (2) comprises a base (4) and a side wall (5) connected to the base (4), the base (4) and the side wall (5) defining the cavity (3); the side wall (5) is defined by a plurality of segments (6); the side wall (5) has an at least partially reflecting inner surface (5a) and an outer surface (5b); each segment (6) has a first end (7) connected to the base (4) and a second end (8) opposite said first end (7); the reflector (1) comprises a locking device (10) fixed to said second ends (8) and designed to retain said segments (6); the locking device (10) comprises a pair of half-pieces (11, 12) connected to each other and designed to maintain adjacent said second ends (8) of said segments (6).