Examples from the Web for onlooker
The paper reports: “It was utterly shocking to watch,” said one onlooker.
She was wearing an "incredibly low-cut dress," one onlooker said.
There can hardly have been an onlooker who would not have wanted to go up to the young man and shake his hand.
Asked one onlooker motioning toward the crush of people blockading every clothes rack.
(p. 407) "The advance proceeded well from the start," wrote one onlooker.
But a factor of all was that Lulu herself was the participant, not the onlooker.Miss Lulu Bett|Zona Gale
As an onlooker, of course you see me more clearly than I see myself, and your judgment of me is probably right.Ivanoff|Anton Checkov
But the Onlooker was no dreamer, and he saw her about three times a week.The Literary Sense|E. Nesbit
By the swing of his stride any onlooker would have believed that Cutty was in a hurry to arrive somewhere.The Drums Of Jeopardy|Harold MacGrath