Fort - File encryption software for Windows.
Cryptkeeper - Cryptkeeper is a Linux system tray applet that manages EncFS encrypted folders.
AES Crypt - AES Crypt is an advanced file encryption utility that integrates with the Windows shell or runs from the Linux command prompt to provide a simple, yet powerful, tool for encrypting files using the Advanced Encryption Standard (AES).
Windows BitLocker - This topic provides a high-level overview of BitLocker, including a list of system requirements, practical applications, and deprecated features.
GnuPG - GnuPG is a complete and free implementation of the OpenPGP standard as defined by RFC4880 (also known as PGP).
VeraCrypt - VeraCrypt is a free open source disk encryption software for Windows, Mac OSX and Linux.