knight in shining armor
A selfless, chivalrous man who helps a woman in distress. When the police officer pulled over to help the old woman change her flat tire, she hugged him and said he was her knight in shining armor.
white knight
1. One who saves another person from harm or a difficult situation. I don't remember much from the accident, but I am forever grateful to the white knight who freed me from my car. When Sally came to help with the kids when I was in the hospital, she really was our white night.
2. A person or company that purchases, or gives money to, another company that is in financial distress or about to be acquired by a third party. We all thought we were going to lose our jobs, but then a white knight purchased the company and saved it from bankruptcy.
all-nighter
1. The act of staying up all night to complete an activity, usually some kind of academic project. I'm going to have to pull an all-nighter if I'm going to get this term paper done in time for school tomorrow.
2. An establishment that remains open all night. Kyle and Amanda stopped at an all-nighter for a snack after the concert.
3. One who stays awake all night. Jess is a total all-nighter, so that third-shift job is perfect for her.