When referring to an author, such as in a book report or essay, should I use their pseudonym or their real name when I am speaking about them or their works? Thanks!
Using the pseudonym is a better choice, out of respect to the author, and other names can be dealt with separately.
e.g. You don't refer to Lewis Carroll as Charles Lutwidge Dodgson when talking about Alice in Wonderland, wouldn't you?
Neither would you refer to Lemony Snicket as Daniel Handler when referring to A Series of Unfortunate Events, etc.
But if they wrote different work under different names, then you would bring up the other names if it is worthy to mention so.
ex. The Cuckoo's Calling was written by J. K. Rowling, under the pseudonym of Robert Galbraith.
Or in general, "X wrote (some work written under another name) under the pseudonym/alias/whatever of Y."