- Seraph: an authentication module. verifies that connected users are who they claim to be (by fighting them).
- The Oracle: a random number generator. nothing she says is supposed to "make sense" but random elements are required to make the other (deterministic) programs in the matrix work correctly. her advice is not of any use to the protagonists (being human, they have sufficient built-in randomness). her advice is also erroneously taken to be genuine oracular output by the "smith" virus.
- The Keymaker: a security module. generates security tokens (or "keys," which are portrayed as actual physical keys). once the protagonists have the keymaker, they can presumably enter even the most secure parts of the matrix using forged security tokens.
- The Merovingian: a system administrator, probably of higher rank than the "agents." messes around in his spare time using the excess capacity of the matrix. fails in one of his primary duties (maintaining the security of the keymaker).
- The Twins: powerful investigative tools available to the system administrator. the twins are possibly universal debuggers of some kind, or at least they have a very-low-level interface to the matrix. if one twin is maliciously modified, it can repair itself by overwriting the damaged parts with "good" copies from the other twin. to win, both twins must be disabled simultaneously.
What a dumbass post; I never thought I'd sink to this level, but here I am all the same.