DaisyDisk - DaisyDisk is a disk analyzer tool for OS X that visualizes hard disk usage and allows to free up hard disk space.
SDelete - Securely overwrite your sensitive files and cleanse your free space of previously deleted files using this DoD-compliant secure delete program.
CleanMyMac X - Clean, protect and speed up your Mac
CCleaner - CCleaner cleans, speeds up and frees up space on business endpoints.
MacFly Pro - Smart assistant for better Mac performance
Clean Master - Some users swear by it, some call it a glorified snake oil that does more harm than good. That can be said about any snake oil, but what specific brand of snake oil can boast almost a billion downloads around the world?