First, a definition: Fan films are movies made by people outside the entertainment industry who write or improvise a script set in a familiar universe (like “Star Trek” or “Star Wars” or “Batman” or “Harry Potter”) and shoot it themselves.
It’s not illegal as long as nobody makes any money from it — although some companies, Marvel in particular, don’t like their characters and worlds messed with. Anyone can do it, but it’s not easy. Time-consuming. Costly. And if you want to do it really well, there are actors, special effects, props, background music, costumes, makeup and distribution to consider.
That’s when making a small fan film becomes a Herculean labor of love.