This trope is common in media where there is someone who feels the need to keep track of multiple kills. Pilots in war films usually slap a Custom Decal on the nose of their plane to denote how many enemies they've taken down. It's not just a boost to the pilot's ego, but a morale boost to the entire squad and a demoralizer to the enemies. Serial killers also keep a kill tally as a Creepy Souvenir. Some even do the tally on their own bodies making themselves a Human Notepad. In Lighter and Softer works, the tally may mark down victories at a sport or challenge. If you have two or more people doing this to compete at who's the best at taking down enemies, that's Body Count Competition.
- Con Air : Serial rapist/murderer Johnny 23 had a tattoo added for every victim.
- Pacific Rim: Striker Eureka had little Kaiju stamps on its chassis to mark its kills, especially because it had the highest number of kills.
- One of the Universal Soldier movies had a titular soldier who wore his kill tally as a gruesome keepsake: a necklace with the ears of his kills strung like beads.
- World War II movies (not a genre I'm familiar with so titles would be needed)
Hello, Unknown Troper. You'll need to get known to lend a hand here.