Here's Infocult's 2011 list*. It's not a complete summary of Gothic film, but a mad sampler. It'll give you a sense of horror movies' breadth and diversity.
Some of the titles are famous, some are obscure. Some are canonical, while others are here for sheer weirdness. Most are from the US, but other countries are here as well.
Each one gets named, IMDB-linked, an image or video clip, plus a sentence or two of justification. See them all:
Dracula (1931) (Spanish-language production). One of the great monster movies, helping kick off that subgenre. Browning/Lugosi's is terrific, but this version is fascinating.
Black Cat (1934). A staggeringly weird, beautiful, and melancholy film. Karloff and Lugosi face off through time and bystanders, engaging in murder, drugging, torture, flaying alive, chess tournaments, and very strange dialogue. An unusual take on WWI, too.
The Bride of Frankenstein (1935). "To a new era of gods and monsters!" An exuberent film, an imaginative sequel to the first great Frankenstein film (1931). Everything is good here, from the bride's outrageous look to the sheer madness of Praetorius. The heart requisition scene is worth the whole show.
Gods and Monsters (1998) is a fine film reflecting on this era, among other things.
Pyscho (1960). Probably the greatest psycho killer movie. It's also noteworthy as a genre mashup, starting off as a sleazy crime story ("if any of [the money is] missin' I'll replace it with her fine, soft flesh!"), grafting itself onto Gothic, mashing the two together, then ending up with a micro-psychological thriller.
Peeping Tom (1960) The classic audience-indicting movie, both for making horror watching a plot point (ahem), and for a case study in career dooming. There's also an interesting technological angle, with devices forming fear's basis.
Black Sunday (1961) On the one hand it's a gorgeous mix of contemporary Hammer-Horror-style style: ancient castles, curses, gorgeous women, monsters, all done in a stagey, over-the-top way. On the other hand it's Bava (not this Bava), and partakes of the impending insane Italian horror school.
The Haunting (1963). A masterpiece of quiet terror, this film version of Shirley Jackson's novel is based on never showing the monster. Curse of the Demon almost did it in 1957. PS: there is no remake.
At Midnight I'll Take Your Soul (1963). The Brazilian Coffin Joe movies are hard to describe. They build on Hammer-level gore, then advance to 1980s buckets of blood. They have a demonic antihero (a psychotic, Lautreamont-like undertaker), religious plotlines, and gratuitous violence. There's isn't much like Zé do Caixão.
Onibaba (1964). Another war-related movie, Onibaba starts with murder, mutilation, and robbery, then gets crazy. Two women eke out a living by ambushing war-fleeing samurai, until the younger one falls for a returning soldier. The older one uses a demon mask to terrify the lovers, and things go very badly.
Night of the Living Dead (1968). Not the first zombie movie, but probably the best. A marvel of low-budget filmmaking, Night sics horror into everyday life with one of the best monster reveals ever, setting up a nearly continuous level of terror.
Bonus points: the whole film's in public domain, so you can download it from the Internet Archive.
The Exorcist (1973). Helped set off a series of horror trends, including increased gore. The religious fear aspect reaches back to the foundations of 18th-century Gothic. Also has a splendid backmasking scene ("I am no one!").
Wicker Man (1973). Anothe genre-mashup, this combines horror with police procedural. A fun satire on contemporary back-to-nature culture, with a dark slash of mythic reconnection. Christopher Lee adds a jolt of power to the whole thing:
Alien (1979). The greatest sf/horror film, this combines a splendid monster (which became a franchise) with digital techologies. It also owes a lot to Bava's insane Planet of the Vampires (1965), which terrified me as a child.
The Evil Dead (1981). A low-budget gorefest, one of the HP Lovecraft-oriented films in this list, and an early part of the 1980s teen slasher movies.
The Nightmare Before Christmas (1993). A holiday-themed horror movie which isn't a deathfest, and one entirely made out of stop-motion animation, this delightful confection played a vital role in grounding the Goth subculture's identity.
Seven (1995). Another religiously-grounded horror film, Seven managed to outlast all but one of that decade's serial killer movies. Influential, and deeply bleak, ultimately heartbreaking, it pairs well with the underrated near-contemporary Dark City (1998).
Blair Witch Project (1999). Another low-budget success, Blair Witch is perhaps most famous for its successful Web-based promotional campaign. It also draws on the rich Gothic hoax tradition.
Tale of Two Sisters (2003). A rich, ambitious Korean film, a great take on the haunted house story Tale's nature and emotional heft only comes clear in the awful, final scene. It's not a surprise ending, like Sixth Sense's (1999), but a novelistic completion. The film reflects a deep awareness of horror film tradition, and thus ends our sampler neatly.
I've left off tons of stuff, obviously. Add your suggestions in comments, or wait 'til next year's.
*Why 18 films? 6+6+6, of course.