Vampires don’t appear in mirrors – everybody knows that. It’s in the job description. It’s a feature in a lot of vampire movies, and has been used in countless vampire jokes. It’s a defining feature of the Undead.
Except, of course, that it really isn’t. The Undead weren’t Unseen in mirrors throughout their folkloric history, nor in pop culture from their blossoming in the early 19ith century through practically the end of it. Bram Stoker invented this “fact” about vampires for his novel Dracula, which not only codified the system of beliefs about vampires, it also made a lot of it up. This is one of the things it made up.
At first glance, you’d think it WAS a legitimate piece of folklore – it certainly looks like one. The mirror captures or reflects the Soul, after all, and vampires have no souls, so they have no reflection, right? (Oddly enough, nobodsy has any problem with vampires showing up in photographs, or on television. And vampire shadows are an entire subject to themselves in vampire movies – look at Murnau’s Nosferatu, Dreyer’s Vampyr, and Coppola’s Dracula, all of which use shadows to eerie effect.
So Stoker invented the lack of reflection, then, of course, he used it to dramatic effect. This also shows up in the Dean/Balderston stage play Dracula and in the movies derived from it, where Van Helsing uses this to demonstrate to Dracula that he knows what he is.
So you’d think that, if any vampire would lack a reflection in films, it’d definitely be Dracula, right? Only it’s not true. In at least two films, Dracula definitely reflects in a mirror. This can’t be a mistake - every element in a movie is put there deliberately. If they realize that they made a mistake, they can re-shoot a scene.
Nosferatu is so obviously an uncredited (and non-royalty paying) ripoff of Dracula that Stoker’s widow won court cases against the company that made it, and destroye every copy she could. In some prints, in fact, the Count isn’t called by his official name “Count Orlok”, but is frankly called “Dracula”. So it seems really weird that, at the very end, as he is about to die, he is ostentatiously shown reflected in a mirror (almost at the very end, about 1:22):
https://video.search.yahoo.com/video/play;_ylt=A2KLqIVjKR1V.RsAUyz7w8QF;_ylu=X3oDMTByZWc0dGJtBHNlYwNzcgRzbGsDdmlkBHZ0aWQDBGdwb3MDMQ--?p=Youtube+Nosferatu&vid=27461e6a71f2801276bb77a98a123a7a&l=1%3A24%3A20&turl=http%3A%2F%2Fts4.mm.bing.net%2Fth%3Fid%3DVN.608056254534059971%26pid%3D15.1&rurl=https%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DrcyzubFvBsA&tit=Nosferatu+(1922)+-+Full+Movie&c=0&sigr=11bke0a8l&sigt=10t6770ii&sigi=11r4modms&age=1231016320&fr2=p%3As%2Cv%3Av&fr=yfp-t-252&tt=b
Another case occurs in the 1948 film Abbott and Costello Meet Frankenstein – the last gasp for several of the Universal monsters of the 1930s and 40s, and only the second time Bela Lugosi played Dracula on film (although he played other vampires before and after this). Bela had played the mirror scene countless times on stage, as well as in the Tod Browning film, so he was hardly unaware of this facet of Dracula. Universal made the film, so they certainly knew. But at 0:55 on this trailer, you can clearly see Drac reflected in a mirror that had to be deliberately placed there:
(Added – I hadn’t even realized that a color trailer for this existed. As far as I know, this is the first time that the Frankenstein monster was officially recognized as being Green. The previous films were black and white. Some posters depicted him as green, but others showed him with normal flesh tones. Some colored lobby cards showed him green, IIRC, but this is the first and AFAIK only color footage showing the monster intended for any sort of release.