Athletic supporter may refer to:

• Jockstrap
  Jockstrap
  A jockstrap is an undergarment designed for supporting the male genitalia during sports or other vigorous physical activity...
  
  , men's undergarment designed for use in sports
• Booster club
  Booster club
  A booster club is an organization that is formed to support an associated club, sports team, or organization. Booster clubs are popular in American schools at the high school and university level...
  
  , contributes money to an associated club, sports team, or organization

This is a term used to describe the individuals who hang around athletes at the Collegiate and Professional level, but are not athletes themselves. This term is intended to be a derogatory description, often used by families of athletes describing the "groupies" that often are around athletes.