Panagiotis Verdes is the Greek inventor of the 6x6x6, 7x7x7, 8x8x8 and 9x9x9 Twisty Puzzles. He has also worked on new designs of every Twisty Puzzle from 2x2x2 to 11x11x11.
Panagiotis Verdes Wikipedia
Prior to Verdes's invention, the 6x6x6 cube was thought to be impossible due to geometry constraints. Verdes's invention uses a completely different mechanism than the smaller Rubik's cubes; his mechanism is based on concentric, right-angle conical surfaces whose axes of rotation coincide with the semi-axes of the cube. The patents for the cubes were awarded in 2004, and mass-production began in 2008. Verdes's mechanism allows cubes of up to size 11x11x11, as larger cubes have geometrical constraints.