I love evolution gives us fish with saw in their head, fish with hammer being their head, fish that walks on land, multiple species of fish that literally breath but cannot go near land, a deer with extremely long neck, an animal that have two teeth sticking out of its mouth and eats with its long nose.
But a horse with a single horn, sorry man, that is too farfetched.
Missed opportunity for a narwhal in the third pic
Mosquito: Disease-vector unicorn
The middle picture is not a unicorn it is a twonicorn.
Or as we say in the industry, a bicorn (note that there is currently no industry that refers to them as bicorns)
You could add a mosquito to the list as a stealthy infiltration and light assault unicorn.