When Stan Lee died on November 12, 2018 at age 95, he left a hole in the world of superheroes that he helped create. He also left behind a few surprises: In addition to his posthumous cameos in Captain Marvel and Avengers: Endgame this year, the comic book writer contributed to a class on superheroes that's now available on edX.

The SmithsonianX course, titled "The Rise of Superheroes and Their Impact on Pop Culture," traces the history of the genre from the Golden Age of comic books to the Marvel Cinematic Universe. Before his death, Stan Lee helped shape the curriculum as a virtual instructor. He's joined by instructors Michael Uslan, executive producer of The Dark Knight series; David Uslan, a comic book publisher and Michael's son; and Christopher Robichaud, a professor who writes about superheroes and philosophy.

While learning about the history of superheroes, students will get a lesson on American history at the same time: The class covers Word War II, the McCarthy Era, and globalization through a comic book-tinted lens.

You can enroll in the six-week course for free through edX, or pay $50 to pursue a verified certificate. Here are some more online courses you can sign up for in 2019.