Bystander (noun)

1. A person who is present at an event or incident but is not directly involved.
2. A person who watches events happening without taking part.

Origin:

Late 17th century: from by- + stander.

Examples:

1. He was just a bystander who was caught up in the events.
2. She was a bystander at the accident and she called for help.
3. The bystanders were horrified by what they saw.
4. He was just an innocent bystander who got caught in the crossfire.
5. There were many bystanders who witnessed the altercation.