Brute and Glob

Jack Kirby

Brute (right) and Glob (left) as they appeared as drawn by Jack Kirby

The duo were originally sidekicks to the Garrett Sanford Sandman, who fought nightmares in "the Dream Dimension". They were contained in domed cells. They would be freed when Sandman blew into a magic whistle. Brute and Glob were nuisances that were fairly well-intentioned and harmless.
Neil Gaiman

Their darker and edgier counterparts

Sandman got a dark revamp with a new version of Sandman taking the role. Brute and Glob were revealed to nightmares that went rogue when Dream (the actual Sandman) disappeared. Brute and Glob were manipulating Garrett in the hope of having a dream lord under their control. The Dream Dimension was just a small corner of the Dreaming (the dream world of the DC universe) that the duo cut off from the rest of it. However, Garrett snapped under pressure and killed himself. So, they took the ghost of Hector Hall and made him the new Sandman (since he couldn't kill himself). They allowed Hector bring his wife in the dimension. However, Dream (having been freed after decades of imprisonments) imprisoned Brute and Glob in "the darkness" and sent Hector Hall to the afterlife.
Later Appearances
Brute and Glob were minor villains in JSA and Lucifer. In their JSA appearance, they reveal what is actually in the darkness that they fear: pleasing dreams of children.
References:
http://en.wikipedia.org/wiki/Sandman_(DC_Comics)
http://sandman.wikia.com/wiki/Brute_and_Glob
The Sandman Volume 2 "The Doll's House"
http://en.wikipedia.org/wiki/List_of_characters_in_The_Sandman#Minor_dreams