Thanos may be the most powerful being the Avengers have ever faced, but there are threats out there not even he can defeat. Now, a recently released book may unveil powerful insight into how Avengers 4 will unfold when it hits theaters next year, and it may involve an entity even the Celestials fear.

In a new book called Thanos: Titan Consumed, the Mad Titan's origins are again rehashed, with insight on what put him on the path to snap half the universe out of existence. By now, we all know his upbringing wasn't roses and sunshine, so his lust for powerful isn't a surprise. However, what is interesting is the fact that his power may pale in comparison to a larger threat.

Toward the end of the book, Thanos meets a character known as the Lorespeaker, kind of like Red Skull's role in Avengers: Infinity War. Basically, the Lorespeaker warns that not only should Thanos be weary of the Celestials, but of a group or single entity that the Celestials fear.

"They are hidden, Thanos," the Lorespeaker said, as though badgering a child, "because they are too powerful. And because the Celestials and the others, the ones whom the Celestials fear, keep close watch on the Stones from afar."

We've heard a few different theories about the possibility of Marvel introducing a powerful cosmic entity in Avengers 4. This latest tidbit from Thanos: Titan Consumed could hint even further at something far more dangerous lurking out there in the universe.

We also recently saw supposed merchandise for Avengers 4 suggest the heroes would face "an even greater threat" when the film is released. Surely, Marvel has one more plot twist up its sleeve before the Thanos storyline concludes.

What's important to note, however, is that Thanos: Titan Consumed isn't canon, so it doesn't tie directly to anything that's happened on the big screen. Still, author Barry Lyga worked closely with Marvel on creating the book, so it still may hint at what's to come.

We'll find out when Avengers 4 hits theaters on May 3, 2019.