Too many situations to pick from.
On a 4 day church backpacking trip in the Sierra Nevadas, someone in our group wanted to get a picture of a bear. He mixed a concoction of oatmeal and fish guts around camp to attract the bears. That was a bad idea. At night, the first bear that came into camp stood outside the guy's only tent door as it stared me down from 20 feet away. I used a flashlight to see the bear and yelled for help. The bear left the area. That night, a group of bears ransacked our camp for food and trash. We temporary scared individual bears away with flashlights and camera flashes.
This June, my dad and I hiked up Mt. Whitney. We started at midnight and hiked throughout the night. Most of the trail was next to a cliff. Many parts of the trail were covered with snow. Some stream crossings were right above a waterfall. We wouldn't have survived without good flashlights and headlights.
I have been on many local night hikes where rattlesnakes, scorpians, and black widows are abundant. I have had to jump over a few rattlesnakes at night to get back (they lay across the trail). I wouldn't have seen them without a flashlight.
During the Witch fire, my family was evacuated from Ramona (birthplace of the two largest fires in California history-Cedar and Witch fires). We went 5 days without a real home. One day in a mall parking lot, 2 at a Motel 6, and 2 at a church in Lemon Grove. The smoke filled sky made it dark for most of the time. I took my supply of flashlights, but I left my Freeplay radio and Sherpa flashlight at home in the rush to get away. When we got home, we had no water. I hadn't done laundry in two weeks. One week was spent with with relatives as my mom died from cancer and we had her funeral the day before the fire. The other week was spent evacuated, then unpacking once we got home. We had another week at home before we could use the water. It was shut off to give firefighters enough water pressure to use their hoses. Apparently, the Ramona water district let their 50 or 60+ year old pump system blow a fuse that took them a long time to replace (they probably weren't made anymore). The backup system hadn't been functional for months. I'm sure you can understand why most of the town refused to pay their water bill when they got home. I had some friends who lost power and wouldn't get it back on for two weeks. I gave them all my loan out/ cheaper lights. They needed them more than I did. There were many people who were worse off.
When working for my dad wiring up a clean room at the University of Arizona in Tuzson, we worked all day in the dark. The worklights we did have were constantly being turned off as drywallers borrowed/stole our extension cords and safety inspectors cut the ends off our cords if they didn't have a ground. My Gerber LX 3.0 got a lot of use and was smacked hundreds of times on steel and concrete. It never stopped working. On my last day working there, I got trapped between floors in the freight elevator on a Saturday. My dad called 911 and in half an hour I was free to take the 10 hour drive home. We were the only ones working that day and the elevator wasn't lit well. My flashlight helped my sanity a little. It was the end of a 10 hour shift.
On a camping trip at Dos Picos park during an extreme fire ban (they wouldn't let me use a candle lantern in my tent and my Whisperlite stove had to be used in the firering with heat reflector and windscreen on with a gallon of water nearby to put it out in order for the ranger to let me use it) I saw a pair of eyes in the darkness near my camp. I put my Fenix P3D Q5 on turbo to see what it was. It was a mountain lion and the light blinded it and scared it away.