SAFER
A 1993 block cipher built to run fast in software, and a good example of how the key schedule can become the problem.
SAFER (Secure And Fast Encryption Routine) was designed by James Massey at ETH Zürich in 1993. It is a block cipher with 64-bit blocks, built to run quickly in software without special hardware, using a substitution-permutation structure with key-dependent rounds. The first version, SAFER K-64, drew criticism for its key schedule, and its designers revised it several times.
SAFER+ was one of the candidates in the AES competition but was not among the five finalists. Early versions of Bluetooth used a SAFER+-based algorithm for authentication, a good example of how a cipher can live on in standards long after it stopped being the first choice.