From the second two in the
Marathon trilogy.
An ancient AI/god created(?) by the S'pht. You help to activate, and merge him with Durandal in Marathon 2. It is never completely clear whether he is actually an AI, or a god, or both. He seems to embody "active neutrality". That is, he tries to maintain balance in the universe by always fighting for whatever side happens to be losing.
He is given to making cryptic remarks, and (in Marathon Infinity) flinging you through time. Here is an example (from Beware of Abandoned Rental Trucks):
Glyphs never understood while
[?young?alive]
now reveal the end of my creation:
When one of foreign speech
casts a [?papyrus] yoke upon the
marsh,
Bethink you to keep the
[?bleating goats]
far from Lh'owon.
His messages do
make sense, but only after you've play the game
4 or 5 times. An excellent (and long) examination of
Thoth is available at the
Marathon Story page http://marathon.bungie.org/story/thoth.html