A conveyor roller or pulley includes an axle portion mountable to opposite sidewalls of a conveyor and a roller portion rotatable relative to said axle portion. The roller includes a braking device positioned at least partially within said roller portion and selectively operable to restrict rotation of said roller portion relative to said axle portion. The braking device may be biased to restrict rotation, such that the braking device restricts rotation when an actuator of the braking device is deactivated, and allows substantially unrestricted rotation when the actuator is activated. The actuator may be activated when a drive motor of the conveyor is activated to drive one of the rollers of the conveyor, and may be deactivated when the drive motor is deactivated. The conveyor may comprise a roller conveyor or a belted conveyor.