Is the term "graphic novel" restricted to works of fiction?

I have always understood "novel" to refer specifically to a long, written, fictional tale. Novelists are distinct from nonfiction writers.

At my library, there is a section marked for "graphic novels" that contains both fiction and nonfiction. Wikipedia claims repeatedly that "graphic novel" just has a looser definition than "novel" and is not necessarily restricted to works of fiction but I notice that these repeated claims are not supported by citation, whereas the version of the definition that's explicitly restricted to fiction is cited as coming from Merriam-Webster.

I understand that there are different camps with regard to what makes a definition "correct" or not. What I'm concerned with here is clear communication. An increasing number of biographies, autobiographies and historical accounts seem to be using this format; if I refer to them as "graphic novels," am I giving the false impression that they are fictions? Is there a contemporary term for long-form, graphic nonfiction works that's less ambiguous?

No, its not. There are quite a few non-fiction works that have been published in this form, and modern ones are still typically described as "graphic novel"s.

To provide a specific example, there's March, the graphic novel covering the US Civil Rights movement from the point of view of John Lewis. It's essentially^* a biography of the period, in graphic novel form.

Since I'm on the subject, I should also mention Martin Luther King and the Montgomery Story, published in 1957. Not only did it inspire March, but it inspired John Lewis to participate in the events depicted in March.

There are quite a few more though. Our local library has a whole shelf of graphic novel biographies. I have noticed that at least some people have trouble with this. A lot of official sources seem to prefer to use the term Graphic Nonfiction. But people without editorial standards boards standing over them smacking rulers into their palms in anticipation of grammatical misdeeds seem to just prefer to use the term "graphic novels" for nonfiction works as well.

^{* - I believe the modern setting scenes are somewhat fictionalized, but the flashbacks are autobiographical non-fiction.}

The definition of 'graphic novel' is correct to mean works of nonfiction and fiction.

Truman Capote coined the term 'nonfiction novel' in 1965 for his work 'In Cold Blood'. If we are to assume there is a such thing as a 'nonfiction novel' then of course a 'graphic novel' can refer to fiction or nonfiction since the word 'novel' is not mutually exclusive to works of fiction.