Many of my photo-shoots use a single light. I like the look and it's easy to set up & shoot. During a recent photoshoot with model, Eclipse Monday - nope, not her real name, I used 3 different lighting setups. However, I always started each look with this single light setup.
The setup consisted of a single Elinchrom D-Lite 4-IT studio strobe. This strobe has been replaced with the newer RX4, but fundamentally the same light. Mounted on the strobe was an Elinchrom 27" beauty dish reflector. As in the past I used a white diffuser sock, but didn't use the internal deflector. I mounted the light directly in front of my model about 8-9' away from the background paper. The light was mounted on a Manfrotto boom arm about 7' high (measured from the center of the beauty dish) aimed down so the hotspot of the light was pointed at my model's face. My model was standing about 3' away from the seamless background.
The goal of this setup was to light the face & upper body with subtle light fall off below the knees. Also, the shadow was directly behind & below my model. This is different from what I normally shoot which is 45/45 (45 degrees off axis camera right from my model / 45 degrees down - or more or less) that throws the shadow camera left.
As always I metered my light at 1/160, ISO 160 & f/9. This has been my go-to camera setting as a starting point for some time...of course in Manual mode.
Of course you can do this with any similar sized beauty dish or deep parabolic. I think it's a cool look.