Marshall is an occupational surname, not having to do with anything military or martial, but comes from the Norman French for someone caring for horses. It's been used as a first name since the nineteenth century and has been on the Social Security list since it started to published its data in 1880. Marshall currently ranks at Number 328.
Marshall is the real name of rapper Eminem doesn't make Marshall any cooler and got some attention during the heyday of communications maven Marshall McLuhan. Peyton Manning named his son Marshall, and Jason Segal plays the central character of Marshall on How I Met Your Mother.