K6 or K-6 may be:
1. K6 (Mountain) mountain in Pakistan
2. AMD K6, a computer microprocessor
3. K-6 (Kansas highway), a state highway in Kansas
4. Sonata in C for Keyboard and Violin (Mozart) was the sixth work by Wolfgang
5. Amadeus Mozart according to the Köchel catalogue.
Transportation:
HMS K6, a British submarine
USS K-6 (SS-37), a 1914 United States Navy K-class submarine
Ka 6, a glider manufactured by Alexander Schleicher GmbH & Co, Germany
https://en.wikipedia.org/wiki/K-6