Those are Mirelurk Kings, the Mirelurks are mutated crabs.
I like all your ideas. I think it would make sense and would provide already a good amount of critter variety.
Thank you but most of these are not my own creations, only the newly suggested Slobbers are.
All of these come from finished Fallout projects or proposed Fallout projects like Van Buren and Fallout Online.
This was one idea I was thinking of when I tried to combine humans with animal traits (no not furries, more like humans with animal senses), blind humans or humans who no longer have eyes due to mutation with a sort of radar sense like bats. (their eyes and the space these use to occupy being replaced with some kind of radar organ)
They would be perhaps pale, hairless and very lanky looking but I don't have them in mind as blood sucking vampire types.
Alternatively using inspiration from the Known Space stories that I read there mutants-with-radar-sense would be naturally armored, perhaps somewhat bulky looking.
But despite their fierce appearance to would be in general non aggressive towards outsiders.
I would call them Grendels after the poem and the Known Space story with the same name.
As for new plant mutants, other than of course the return of the giant venus flytraps I would suggest the following.
Weedling, Carnivorous Bush, Thornslingers (think a pissed of cactus), Stranglevine, Man-traps (plants that trap and eat humans/human mutants), and I had been thinking of some kind of fungus or moss but that may be to much like the Slobbers but in plant form.
I had also been trying to think of ideas for radioactive type of mutants such as Radiation Flyers (think something like a butterfly type creature with an eerie glow due to the radioactive material in its body), or some type of radioactive will o wisp like creature or phenomenon. Creatures people would encounter at certain radioactive areas in the wasteland.
But perhaps these two are more suited to the Wasteland universe than the Fallout universe