I agree with darth_paul... don't wanna have it too broad.
It's a communications class? - do you have to do this as a speech in front of class? Might affect your choice. If it's just a written paper, can play on the teacher's expectations and be more intimate about... hell something about superheroine bondage throughout the 20th Century
Possible ideas to narrow the theme...
1) Batman is really just a new variation on Shakespeare's 'Hamlet' basically. This paper theme would blow your comm prof away, but you'd kinda have to know the major themes/concepts of Hamlet. But consider Batman never thinks about his Mom. Alfred has become his mother essentially. Bruce Wayne is the prince who is to inherit the throne of his murdered father. He spends all his efforts to solve murders to find the truth, motivated by his own father's murder, but he never really discovers the truth he searches for even though he solves other (palace) mysteries. Gotham is the palace. If your prof is into literature he/she'd shit a brick. Just go with it and make it up.
2) Was Superman's death the first really popular death of a superhero? Did Superman's death start the trend of killing heroes to sell comics? Could explore that whole concept.
3) I think to the jewish geniuses who created Superman he was Moses, not Jesus. A foreigner taken in as one of THEIR own only to discover he was a chosen of Yaweh... not as exciting unless you're into theology though. Moses is thought to be Egyptian royalty only to show that he is hebrew and then to show the egyptians that he has supernatural powers bestowed upon him... yadda yadda
4) How the 1970's Superman movie saved DC comics from complete collapse as Marvel was taking over the market. This kind of stuff you can do a lot of personal opinion on unless your prof is a comic buff.
5) Single it out to one character through the years, like your initial idea. How has a major superhero's public persona changed over the years? How have different writers/artists portrayed them? Did the last Superman movie REALLY kill him for real? - ha ha. Batman has more of a change to work with though. Consider the folks who love the 1960's TV show Batman and the now very real and gritty Batman... and all the different artists who have worked with Batman... easy paper to write there.
6) Ethnic heroes throughout the years. Milestone, etc.
7) Your personal journey in comics... how you got first interested... how you've followed it through the years... where you are now... how HeroMorph artists render half nekkid beauties that give you wood... wait, no that's my journey - ha ha. But seriously, that's a great angle. Tell your personal journey with comics. What heroes you started out loving... who you love now... why? what happened to them and you... yadda yadda.. good content stuff there.
8)Explain why Julie Newmar is the best CatWoman. I could write a book about it myself
9) This sounds like BS but it will truthfully fascinate most non-comic fans... if you've been to a comic-con... write a paper on the entire experience. Most people have no clue.
10) Write about Heromorph. say how hero comics have some folks so much they spend hours upn hours devoting time to celebrating this stuff. They make 3d models. They recreate the characters. they make fan fiction comics. They create whole sites dedicated to superheroes... well, mainly superheroines... we've grown up and realize witch sex is really the most powerful
11) Beg Jinky to be interviewed... she has a very compelling life story herself.