This is a recent portrait of Lewis taken at the studio. This is an example of a low key shot because the darker background and single light offer strong contrast between the shadow and highlight areas. Using a softbox has made the light more diffused and it’s close proximity to Lewis also means that the light falls off quickly into shadow (the intensity of the shadow itself is controlled by reflectors).
More specifically this is example of Rembrandt lighting (named after the Dutch painter who often used this style).
The defining aspect of Rembrandt lighting is the triangle or underneath the eye (it is fairly subtle in this photo). Photographers will often tell you that the triangle should be no longer than the nose and no wider than the eye.