K2 has never been summited in the winter. There have been attempts to climb it in winter, but none have been close to getting to the top. In 2012 a vigorous Russian team was aiming for a first winter ascent. The expedition ended on with the death of Vitaly Gorelik due to frostbite and pneumonia. The Russian team cancelled the climb. K2 and Nanga Parbat are the only 8,000-metre peaks not climbed in winter. A number of teams will be trying to climb Nanga Parbat this winter.
Watch this documentary on K2: