DiskCryptor!

VeraCrypt is a free disk encryption software brought to you by IDRIX and that is based on TrueCrypt .It adds enhanced security to the algorithms used for system and partitions encryption making it immune to new developments in brute-force attacks.For example, when the system partition is encrypted, TrueCrypt uses PBKDF2-RIPEMD160 with 1000 iterations whereas in VeraCrypt we use 327670. And for standard containers and other partitions, TrueCrypt uses at most 2000 iterations but VeraCrypt uses 655340 for RIPEMD160 and 500000 iterations for SHA-2 and Whirlpool. »

[TrueCrypt is not exactly "Open Source", but the source is available. See the reviews to get more information.]

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). A Java library is also available for developers using Java to read and write AES formatted files.

LUKS is the standard for Linux hard disk encryption. By providing a standard on-disk-format, it does not only facilitate compatibility among distributions, but also provides secure management of multiple user passwords. In contrast to existing solution, LUKS stores all setup necessary setup information in the partition header, enabling the user to transport or migrate his data seamlessly.

Boxcryptor is an easy-to-use encryption software optimized for the cloud. It allows the secure use of cloud storage services without sacrificing comfort. Boxcryptor supports all major cloud storage providers (such as Dropbox, Google Drive, Microsoft OneDrive, SugarSync) and supports all the clouds that use the WebDAV standard (such as Cubby, Strato HiDrive, and ownCloud). With Boxcryptor your files go protected to your cloud provider and you can enjoy peace of mind knowing that your information cannot fall into the wrong hands. »

No encryption of dynamic disks, but command-line-encryption! Dynamic disks must be converted to basic disks with EasyUS Partition Master or Partition Guru before encrypting with Bitlocker. Windows BitLocker & "Bitlocker To Go" Drive Encryption is a data protection feature in Windows 10 Professional, Windows Vista Enterprise and Windows Vista Ultimate for client computers and in Windows Server 2008. BitLocker protects against data theft or exposure on computers that are lost or stolen, and offers more secure data deletion when computers are decommissioned. Bitlocker To Go (BTG) is essentially Bitlocker for external drives. It’s full volume encryption for all your USB drives: http://blogs.msdn.com/b/rockyh/archive/2009/03/01/bitlocker-to-go.aspx »

LibreCrypt (formerly DoxBox) is an open-source disk encryption for Windows and the successor of FreeOTFE

Cryptonite brings EncFS and TrueCrypt to Android. You can browse, export and open EncFS-encrypted directories and files on your Dropbox and on your phone. On rooted phones that support FUSE (e.g. CyanogenMod) you can also mount EncFS and TrueCrypt volumes. TrueCrypt is only available as a command-line version at this time.

The Gnome Encfs Manager is an easy to use manager and mounter for encfs stashes. It allows you to create encrypted directories, any file that is placed in such a directory will be encrypted.

Cryptkeeper is a Linux system tray applet that manages EncFS encrypted folders.

If your computer were ever to be stolen, are you certain that your personal information cannot be discovered? Jetico’s BestCrypt software automatically encrypts your files so that nobody can read the data unless they have the right password or keys.

FreeOTFE is a free, open source, "on-the-fly" (OTFE) disk encryption program for PCs running MS Windows and Windows Mobile PDAs (FreeOTFE4PDA).

The enterprise cryptographic filesystem for Linux