Gray Jedi are those who, though having completed the teachings of the Jedi, operate independently and outside of the Jedi Council. They are typically seen as misguided, though they have not necessarily succumbed to the dark side.
The personal guards of the emperor of the revived Galactic Empire. Trained to be extremely loyal and disciplined, they were among the most loyal warriors in the Empire. They used the force, but were cautioned about the dark-side. However, they did not show a strict adherence to the light side either. They did lean more towards the light-side, as they swore that they would only serve their emperor if he remained aligned towards the light-side of the force, and if he fell, then their duty would be to either turn him or remove him from office.