przypadkowy świadek in inglese:

The men ran around the park trying to catch the stray dog as a group of onlookers stood and laughed.

a crowd of fascinated onlookers

In many ways the onlooker is just as complicit by their inaction

A crowd of onlookers had gathered at the scene of the accident.

Many innocent bystanders were injured by the explosion.

There were two bystanders who witnessed the accident, but neither of them went to help.

A bystander videotaped the police beating using their cell phone.

The explosion killed an innocent bystander.

i'm like this useless bystander

These instruments detect linear acceleration, tilt and other directional cues to keep them from dive‐bombing the ground or, worse, unsuspecting bystanders.