To have attention or recognition directed away from a person -- either intentionally or accidentally -- to such a degree that no one remembers that person (and in severe cases, could signal the end of that person's career).

This definition comes from the halftime show of Superbowl XLIX on February 1, 2015, when American singer Katy Perry's performance was overshadowed by a dancer dressed in a shark costume -- on her left side -- who appeared to forgot his choreography and danced differently than the other shark-dressed dancer on the right side.