The Hounds of Tindalos are a part of H.P. Lovecraft's Cthulhu Mythos. They dwell in the distant past of the Earth, when normal life had not yet advanced past one-celled animals. They are said to inhabit the angles of time, while other beings (such as mankind and all common life) descend from curves. The hounds are said to be immortal, and to lust after something in mankind and other normal life, following victims through time and space to get it. What those creatures look like is unknown, as their appearance is not described in any Cthulhu Mythos story, due to the fact that every character in the short stories that meets a hound of Tindalos does not survive to tell. Though they are normally pictured as canine beings, due to the evocative name of first story where they appeared—"The Hounds of Tindalos"—it is not likely that they look like such.

The stories tell that because of their relationship with the angles of time, they can materialize through any corner if it is sharp—120º or less. When they are about to appear, they materialize first as smoke pouring from the corner, and finally the head followed by the thing's body emerge. It is said that once a human has been known to one of these creatures, it will follow through anything to get to him.

"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 also turn up in Final Fantasy X-2 as lupine spirit-creatures.