Finished this fantastic game... and I can't believe how much I missed! (SPOILERS)

[GhylTarvoke]

[*]How do you know the names of all those monsters? I can't remember them being named in-game.
[*]How do you know one of them is Akers? I read about him a lot, but... huh?

Shameless plug: here's my thread that names the enemies, based on research by forum members.

Spoiler below!

Only two monsters (Proxy, Anglerfish) are unambiguously named in-game. In many cases (Construct, Crawler, Flesher, Robot Girl, Leviathan, Viperfish), the only way to find the name is to look behind the scenes, i.e. by opening up the editor or digging into the game files.

As WAU said, Yoshida's name appears on a terminal in Tau. Since
1) face-rapey tentacle guy is wearing a power suit;
2) the terminal says that power suit 3 is active; and
3) the terminal says that Yoshida was the last person to access power suit 3,
it's reasonable to conclude that tentacle guy is Yoshida, which is confirmed by the Tau map script.
There's one twist: "/4subjWAUr/" accessed the power suit a day before Yoshida did. I like Science Bird's theory that the suit was "infected" at this point.

Akers is an interesting one. We know that Akers went to Theta with the goal of putting everyone into a WAU-induced "lucid dream" (and apparently succeeded).
One of the enemies at Theta appears to be much stronger and faster than the others. It's also the only one with functioning arms, and hence the only one capable of trapping people in structure gel. The same enemy tries to trap you in structure gel.
It's reasonable to conclude that this enemy is Akers, which is confirmed by the Theta map script.