Horrors in space

There are two things one should have in mind when talking about horrors in outer space:

1. Up til the first physical exploration of space, we were all alone in the universe 
2. Any life out there since then - no matter how twisted or unreal - has its origin down here on Earth 

That is, anything encountered up there is a bastardly remix of something we once sent up on purpose - or just lost by accident somewhere in the thermosphere.

The V-2 rocket (1942)
The first rocket to reach outer space, actually never returned to Earth despite common belief. Became sentient and suicidal after being exposed to a stellar flare in 1981.

40 mice (1960)
Part of the original all animal crew of Korabl-Sputnik 2, these mice never did return safely to Earth. Gnawing through their cage at re-entry, they suddenly hit a power cord just as the shuttle passed through an aurora - causing them to switch places. The caged aurora was never made official.

Имре́к (1962)
Just one of many unofficial and unknown cosmonauts lost during the Vostok programme. At the time, a large translucent mesh passed through our neck of the universe, causing these poor souls to be collected like fish in the sea.

In 1978, a thin purple cord shot out through deep space, attached itself to the mesh and started pulling it in. The cord bumped into the Soviet satellite Kosmos 954, causing it to malfunction and later crash over northern Canada.