Stats - Simple macOS system monitor in your menu bar.
DisplayBuddy - Control the real brightness of your monitors directly from your Mac - no need to touch the buttons on your Monitor.
iStat Menus - "An advanced Mac system monitor for your menubar."
Lunar.fyi - Control monitor brightness, adapt using the ambient light sensor, adjust volume, switch inputs and turn off displays without fiddling with clunky buttons.
MenuBar Stats - Advanced Mac system monitor right from the menu bar
Nocturnal - Have more control over your screen at night 🌙