Which drugs are known to distort the perception of reality and thought processes

The correct answer here is Hallucinogen.

Technically all drugs one way or another distort the perception of reality and thought processes but hallucinogens are especially potent in that regard. Hallucinogens are those agents that can cause, among other things, hallucinations and changes in consciousness, emotions and thoughts. LSD is maybe the most known representative of the hallucinogens.