Clonezilla - Clonezilla is a suite of software that's designed to allow you to back-up and image new hard drives with your data.
Carbon Copy Cloner - Carbon Copy Cloner (CCC) features an interface designed to make the cloning and backup procedure...
Win32 Disk Imager - Create and restore image backups of disk drives.
Duplicati - Free backup software to store backups online with strong encryption. Works with FTP, SSH, WebDAV, OneDrive, Amazon S3, Google Drive and many others.
Macrium Reflect - Macrium Software - the creators of Macrium Reflect backup, imaging and cloning software.
Time Machine - Time Machine is the breakthrough automatic backup that’s built right into Mac OS X.