Answer: bystander

AnswerCrossword Clue
BYSTANDEROnlooker
BYSTANDERWitness
BYSTANDEROne present but not taking part.
BYSTANDERChance spectator.
bystandersomeone who stands by or near one; an onlooker
bystanderA person who is present at an event or incident but does not take part