Yes, there is.

As a glitch in the generation 3 games of Pokemon, a glitch Pokemon appears as a question mark. Its image can be viewed in the related link below.

In any game with unown, there is a question mark shaped unown, and is not a glitch. You must capture the other 26 unown before getting this question mark shaped unown (along with an exclamation mark unown).

The symbol for a question mark is simply called a "question mark."

Question Mark ? is a question mark.

After the question mark.

?