MARS
IBM's AES candidate, one of five finalists in 1999, built around a Feistel core wrapped in unkeyed mixing rounds.
MARS is a block cipher from IBM with 128-bit blocks and a variable key length, led by Don Coppersmith. The other finalists were RC6, Rijndael, Serpent and Twofish. The cipher is a Feistel network of 32 rounds, where a core of keyed rounds is surrounded by rounds that use no key.
IBM claimed that MARS was more secure than triple DES and much faster than single DES. The AES process chose Rijndael instead, but MARS is still studied as one of the more thoroughly analysed candidates.