The planet known for having a Great Dark Spot is Neptune. This feature was discovered during the Voyager 2 flyby in 1989. The Great Dark Spot is a massive storm system similar to Jupiter's Great Red Spot, characterized by its dark appearance against Neptune's deep blue atmosphere. These storms can be several times the size of Earth and are part of Neptune's complex weather patterns, which also include strong winds and changing cloud formations. Since Voyager 2's encounter, the Great Dark Spot has since faded and changed, showcasing the dynamic nature of Neptune's atmosphere.