: See, I'd always interpreted the Hindmost as being one of the "High
: Technology races" the Pfhor sells slaves to as mentioned by Leela in
: "Try Again", rather than being of the Pfhor itself, just a rank
: or two higher up the food chain than them.
Again, the Hindmost Creche is clearly a singular individual, as Tfear uses the pronoun "Her" (note the capital letter, which may be an indication that She has some sort of religious significance to the Pfhor, or at least to Tfear) to refer to the Hindmost in "One Thousand Thousand Slimy Things", which rules out Her being a race (or any sort of group, for that matter):
: The Hindmost is of an intelligence so vast, it encompasses the span of
: the Pfhor, and to those privilege to serve Her, appears insane. That is
: the final function of the Commanding Rank, the thought that we keep
: forever in our minds, that we deny our selfish, willful needs, so that the
: Empire will survive.
This also says that Her intelligence "encompasses the span of the Pfhor". She may be a particularly advanced Pfhor, an artificial intelligence (although that would be unusual, since the Pfhor's own AIs mostly seem to be primitive), a deity in their religion ("Hindmost Creche" may be a metonymy for the "Great Mother crouched behind the Throne" Tfear mentions in "Aie Mak Sicur"), something else entirely, or some combination of the above. In any case, a creche is a nursery or an orphanage, so "Hindmost Creche" probably is a location strongly associated with Her rather than Her actual name.
Beyond stating that the "final function of the Commanding Rank" is "to serve Her", this passage also implies that Tfear belongs to the Commanding Rank. I'm not aware of any other Pfhor known to belong to this rank, and Tfear looks substantially different from any other Pfhor we see in-game (in fact, he looks almost humanoid), which furthermore suggests that members of the Commanding Rank are themselves very high-ranking (and also quite rare).