Upon finishing night 5, (with the purple man's death) A picture is shown that says BAD ENDING
and has a pile of FNaF heads including Freddy, Foxy, Bonnie and Chica. They all have lights in the eyes
as shown in Fazbear's Fright and an extra set of lit eyes can be seen next to the rest.
Now, it isn't quite clear what can be done to correct this "Bad" ending, and it seems all good-
the purple man is dead, the FNaF animatronics were burnt, the souls of the children released-
But something is wrong. Is the purple man good? surely not. But why would his death be "Bad"?
Maybe this "Bad Ending" isn't about the purple man, but the crying child in the minigames not getting
cake in chica's party or in Happiest Day. Who knows? If you do, please comment!
Also, an image I have seen is "Ending" and nothing more. The eyes are not lit and the extra set is gone.
Assuming in the Bad Ending image the extra set was golden freddy and the best ending known so far doesn't have those,
we can probably assume it has something to do with Golden freddy, which may or may not be tied into the whole
purple man thing.
Who knows? Maybe the best we will get is "Ending" and not "Bad Ending".

Perhaps the lights in the heads represent the souls of the children, because
it's nota bad ending when the lights aren't there.