Crack 5.0 by Alec Muffett
Password auditing tool. Performs a guessing procedure to derive a standard UNIX eight-character DES encrypted password.
John the Ripper
A portable password cracker with built-in efficient implementations of multiple password hashing algorithms found on various Unix flavors. Additionally supports Kerberos AFS and Windows NT LanMan hashes, plus more with contributed patches. Officially supported are most Unix-like systems, Win32, DOS.
Unix PW Crackers
A number of utilities collected from various places that all aid in the cracking of UNIX-style password files.