"They are lean and athirst!" he shrieked... "All the evil in the universe was concentrated in their lean, hungry bodies. Or had they bodies? I saw them only for a moment, I cannot be certain."
—Frank Belknap Long, "The Hounds of Tindalos"
The Hounds of Tindalos dwell in the distant past. They are said to inhabit the angles of time, while other beings (such as humankind and all common life) descend from curves. The Hounds are thought to be immortal and are believed to lust after something in humankind and other normal life, and will follow victims through time and space to get it. Because of their relationship with the angles of time, they can
materialize through any corner if it is fairly sharp—120º or less. When a
Hound is about to appear, it materializes first as smoke pouring from
the corner, and finally the head emerges followed by the thing's body.
It is said that once a human becomes known to one of these creatures, a
Hound of Tindalos will pursue the victim through anything to reach its
quarry.Their appearance is unknown because no characters who meet them survive long enough to give a description.
Though the Hounds are sometimes pictured as canine, probably because of the evocative name of the first story in which they appeared, it is not likely that they appear as such. The name Hounds of Tindalos refers more to the creatures' habits than their appearance.
Sources: Howard Philip Lovecraft Mythology, Long, Frank Belknap. "The Hounds of Tindalos" (1931). In Tales of the Cthulhu Mythos (1st ed.), Random House, 1998. ISBN 0-345-42204-X. Lovecraft mentions the creatures in his short story "The Whisperer in Darkness" (1931).
Sources: Howard Philip Lovecraft Mythology, Long, Frank Belknap. "The Hounds of Tindalos" (1931). In Tales of the Cthulhu Mythos (1st ed.), Random House, 1998. ISBN 0-345-42204-X. Lovecraft mentions the creatures in his short story "The Whisperer in Darkness" (1931).