advocate: to publicly recommend or support
What does that actually look like?
Many public and academic libraries allow patrons to "Request a Title" or "Suggest a Purchase" if it is not in their collection. This is one way to quietly advocate for the materials you would like to see in your library.
Want to do something more?
If you're at a university think about serving on your library's advisory committee or getting to know your subject liaison better, since they can help get your purchase approved.
If you're at school, work with your librarian to integrate pop culture materials into your curriculum. Using the materials in your curriculum gives librarians more incentive to purchase those materials for the library.
If you're working with a public library, go to the Library Commission or Board Meetings where there is opportunity for the public to make comments about library services. Volunteer to be on the Library Commission or Board and work with the library district to develop and grow.
There's always a way to get pop culture materials into your library. Think about collaborating with a librarian to write a grant that supports collection development or specific reading program at your library. While not all of the grants listed below focus solely on purchasing graphic novels, comics, or films, it is possible to include those materials in your proposal along with fiction or non-fiction books.