The Flock

The Flock are a herd of demonic sheep, and the remnants of Bill's drove. Technically, they belong to a class of being know as 'nightmares'.

History

The Flock was inherited by Dipper along with Bill's power. It's most likely he first discovered them around the time he worked out he owned his own plot of the Mindscape.

They serve Alcor henceforth. t first coming of as rather enigmatic, he proves to be a good influence on the sheep.

Later, the flock would even come to take 'dreams'- a helpless class of beings that nightmares normally devour- taking the form of lambs under their protection.

Even after the universe ends, the Flock remains. The influx of new energy released when Dipper restarts everything transforms nightmares, including The Flock, into demons, and the dreams into angels.