Semiconductor devices and methods of fabricating the same are provided. The semiconductor devices may include gate electrodes on a substrate. A longitudinal direction of each of the gate electrodes may extend in a first direction, and ones of the gate electrodes may be arranged in the first direction. The semiconductor devices may also include first and second gate spacers extending in the first direction and on respective sidewalls of the ones of the gate electrodes. The first and second gate spacers may be spaced apart from each other in a second direction that is different from the first direction. The semiconductor devices may further include gate separation patterns, and ones of the gate separation patterns may be between two among the ones of the gate electrodes adjacent to each other in the first direction and between the first and second gate spacers.