Normal Responses:

“Flamingo” - One of the devs was so sleep starved, he kept listing off random animals, such as saigas, in a document. Flamingos stuck out the most, however.
“Past” - It is long gone and dead, why do you wish to relive the past? Live in the moment.
“Present” - You are here.
“Future” - Always head, yet you will never get there.
“Death” - Nothing good lasts forever, does it?
“Poltergeists” - German for Noisy Ghost, these spirits are the restless dead, who have yet to find peace.
“Vampires” - Horrific beings of immense power, they feed on the living, draining the life from them. Do not cross paths with them, for they have been given a pact by a horrific being.
“Werewolves” - Vicious beasts, do not let them fool you. At day, they are men, but at night, they turn into wolves, and spread fear into the hearts of men.
“Witch hunters” - Delusional individuals who like to murder anyone who they view as a witch or a heretic.
“Baba Yaga” - A witch who flies around in a mortar and pestle, she might seem kind, but do not let her kindness fool you, she can be just as bad as she can be good. (Note: Baba Yaga has a small chance of spawning after this particular answer)
“Who are you” - Why are you talking to yourself?
“Where am I” - Minecraft is a sandbox video game created and designed by Swedish game designer Markus "Notch" Persson, and later fully developed and published by Mojang.
“What is my purpose” - That is for you to find out.
“Lilith” - A powerful, vampiric demon, she rivals many other demons that conjurers summon in sheer strength alone. Some say she was one of the first things to ever exist, and others say she can grant a powerful gift if bested.
“Watchtowers” - Powerful elemental beings, they can be called upon by a lucky conjurer if they are up to it. But watch out, they are not to be trifled with, for they ARE their element.
“Leonard” - A powerful, demonic mage, he usually aids those in their craft, but as with all demons, he is a fickle being. Do not agitate this entity.
“Demons” - Powerful spirits that can be bargained with for immense power. But they are fickle, and many silly conjurers have lost their sanity, or even their lives, to them.
“Spearfinger” - A horrible witch who disguises herself with magic, she feeds on the livers of children.
“Meaning of Life” - 42
“What are you” - A scrying mirror
“Shadow People” - Fairly similar to demons, these beings appear to the sleep-starved and unlucky individuals at night.
“Life” - A convoluted game all of us play, every day
“Cthulhu” - Ph'nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn
“Muma Padurii” - A cannibalistic witch, she baits children into her house, which she disguises as being made of candy, and stuffs children into her oven.

Conditional responses:
These may occur at under certain circumstances, as opposed to what normally happens if you ask stuff.

“You have way too much free time on your hands, don’t you?” Use the obsidian mirror several times in a row without going away or using other things.