Kiwi application monitor - Kiwi application monitor is a small program which lets you monitor your applications/processes, Windows and User activity.
iStat Menus - "An advanced Mac system monitor for your menubar."
Battle Encoder Shirase - Software that controls per-process CPU usage: an “active” software CPU cooler.
iStatistica Pro - System monitor. Reinvented. 💻 🖥
Processes - https://www.oneperiodic.com/products/processes/
Stats - Simple macOS system monitor in your menu bar.