The Sphinx will have to do for the letter X.
In Greek mythology, this merciless creature has the haunches of a lion, sometimes with the wings of a great bird, and the face of a woman. People who couldn’t answer its riddle are killed.
The Egyptian sphinx had the face of a man and was benevolent. I’m not sure what that means. He guarded an entry, but let people in if they were polite? Maybe that’s why the Egyptian pharaohs hid their tombs, because they knew the sphinx was a pushover. 😛
Both had ferocious strength and were guardians, often flanking the entrances to temples.
What are some good riddles that the sphinx could ask?