In studying for a Sunday School lesson from the book of Daniel (Chapter 1), I've came across a couple of commentaries that suggest that Daniel was a eunuch.
Example:
Have you ever heard this?
Do you believe that Daniel was castrated?
I'm certainly no Bible scholar, but I had never heard that Daniel was made to be a eunuch.
It was a common practice when the king would bring young men into his palace with his wives, concubines and daughters.
Daniel seems to place himself initially under the control of the captian of eunichs, which would indicate that he along with Shad, Mesh, Aben were made eunichs.