On November 10, 2003, at 1145 mountain standard time, a Beech 1900D, N254GL, owned and operated by Great Lakes Aviation, LTD., received minor damage when it collided with a parked airplane while parking at Denver International Airport (DEN), Denver, Colorado. The airline transport certificated captain, commercial certificated first officer, and 11 passengers were not injured. Visual meteorological conditions prevailed. The scheduled domestic passenger flight was being operated under the provisions of Title 14 CFR Part 121. According to the accident report submitted by Great Lakes, the crew was following the marshalling instructions as issued by the marshaller. The taxi speed was slow. The wing walker was behind the airplane and was not able to get around to the left wing. Obstacle clearance was not verified. The left winglet of N254GL struck the right wing of N211GL, another Beech 1900D that was parked on the ramp. The captain shut down the engines and the passengers were deplaned without further incident.