Western Subgenres

The Noir western where the lines are blurred between good and bad. "The Naked Spur" might be an example.
"Johnny Guitar" is also a radically different type of western though I'm not sure how to categorize it.
And how about "High Plains Drifter"? Horror?

A couple of western “caper” films, both with Alan Ladd.

The Badlanders / Delmer Davis (1958). This is often described as a loose remake of “The Asphalt Jungle.” I don’t see it, but some close observers recognize similarities in dialog, especially in the scene where the robbery gang is betrayed by their money man. Also, Anthony Caruso is in both this western and “Asphalt Jungle.” Alan Ladd is a geologist and mining engineer who was framed and sent to prison so a gold strike he discovered could be stolen by an Arizona land baron. When he is released he recruits fellow former inmate Ernest Borgnine and dynamite expert Nehemiah Persoff to help him steal gold ore from a mine shaft lode that Ladd hadn’t told anyone about.

One Foot In Hell / James B. Clark (1960). Ladd puts together a team to bankrupt and ruin the town that he believes is responsible for the death of his wife. Don Murray, Dan O'Herlihy, Barry Coe, and Dolores Michaels (an actress who is impressive here but didn’t have much of a movie career) round out the cast.

Here is a title that may fit the noir western category, but is more of a western and murder mystery mash-up.

Three Hours To Kill / Alfred L. Werker (1954). The plot prefigures a couple of more well-known films that came along a little later. There are the frightened townspeople when a killer returns for revenge as in “High Noon” (1958) and the innocent man who comes near death by lynching and then seeks justice, a theme explored in “Hang ‘Em High” (1968). Dana Andrews is the almost-hanging victim. He wanted to marry Donna Reed but her controlling brother wouldn’t allow it. After brother knocks Andrews unconscious in a fist fight, the brother is shot to death. A mob quickly forms and attempts to string Andrews up, but he gets away with just a wicked rope burn when Reed helps him escape. Now, three years later and tired of running, he returns to find the Real Killer. An old friend of his who has become sheriff allows him three hours, until sundown, to accomplish his task or leave forever lest he be arrested for murder. Suspects abound and, to be honest, I picked the wrong person as the killer. Donna Reed, coming off her Oscar win, is fine as the ingénue in the flashback and as the disillusioned lady with the drawn features in the “present” time. There is some top-notch supporting work from Dianne Foster, Richard Coogan, James Westerfield, and Whit Bissell.

The classic noir “Kiss of Death (directed by Henry Hathaway) was remade as noir western “The Fiend Who Walked The West” (Gordon Douglas) with (later) important producer but terrible actor Robert Evans in the Richard Widmark psycho killer role.

Some modern western films with an international flavor.

The Salvation / Kristian Levring (2014). This is an interesting way to make a western: a Danish film company and director, actors from all over the world, and location filming in South Africa. What they have come up with is a violent revenge thriller set on the American prairie in 1871. Mads Mikkelsen, Eva Green, and Jeffrey Dean Morgan star. The violence quotient, however, is much, much higher that would have been acceptable in the classic era.

Das finstere Tal (The Dark Valley) / Andreas Prochaska (2014). Basically an American revenge western but set in the Austrian Alps and spoken in German. A familiar story but told in an unusual setting and in modern film language. Very interesting movie.

In spite of my long-held contention that all any decent director needs to create stirring cinema is a camera and horses, westerns have never really been my bale o'hay. Those of which I'm fond have been the ones that offer something a little off the well-trodden trail: the lightness, warmth and sincerity of 1939's Destry Rides Again; the introspection of 1950's The Gunfighter; the psychological suspense of 1951's High Noon or 1957's 3:10 To Yuma; the dry wit of 1968's Support Your Local Sheriff; the elegiac melancholy of 1969's The Wild Bunch. So, my tastes in oaters being neither sophisticated nor broadly-informed, I have no idea whether this submission is well-enough represented to qualify as a sub-genre: The Spooky Whodunnit Western.

5 Card Stud (1968) - Standard earmarks are well in evidence: horses and shootouts; ranchers and dusty frontier towns; straight-arrow sheriffs and dastardly lynchings; independent drifters and mysterious strangers; wide-open spaces and abundant sunshine; saloons and poker games. In spite of these elements, old hand Henry Hathaway's film effectively evokes the foreboding mood of an "old dark house" thriller with shadowy figures skulking in the night, atmospherically-whistling winds and a systematic series of murders as the players in an ill-fated hand of the titular card game are bumped off one by one. It's these contrasts that deliver a fair share of the entertainment value, with the mood further enhanced by Maurice Jarre's discordant, minor-key and distinctly un-western music score.

Followers of the whodunnit form will likely have little trouble in sussing out the killer before the official revelation, but the fun is had in the mutual suspicions of those involved in the game and its homicidal results, their cat-and-mouse strategies of detection and survival, and some offbeat casting. Stars Dean Martin and Robert Mitchum comfortably revisit familiar territory with smooth aplomb and western stalwarts such as Denver Pyle and John Anderson are right at home, but Roddy McDowall as a slimy ne'er-do-well, Inger Stevens as an enterprising "shady lady" and Yaphet Kotto as a barman who may know too much add some unexpected interest to the lineup.

The story's pedigree may offer more mystery than the story itself. The basic premise appears to be a reworking of the 1950 urban noir Dark City, and both films were produced at Paramount by Hal Wallis. Yet 5 Card Stud credits only a Ray Gaulden novel, published 17 years after the earlier film, as source material, with the original short story ("No Escape") by Lawrence B. Marcus or his 1950 screenplay with John Meredyth Lucas uncredited.

No matter. 5 Card Stud provides unpretentious but thoroughly enjoyable diversion as a colorful cast of seasoned pros bring their well-honed talents to a horse opera with an intriguing touch of Grand Guignol.    

I despise the traditional western for its ethos but I can warm to some of those which seek to deconstruct it.

I propose the following sub-genres to manfromplanetx, although they may overlap with some already mentioned:

The Ecological Western
Those which deplore the destruction of the environment. This sub-genre has deep roots as conservatives can be ardent conservationists, but it has had a facelift in recent decades.

I have never seen Hud (1963) but a friend called it "The first vegetarian cowboy film". Did he have a point?

The Marxist Western
Depicts progress through class conflict. I would put Once Upon a Time in the West in this group. It is not a Spaghetti Western. It does not even fulfill mfpx's own criteria:
Italian language - NO, mostly Murican
low budget - NO
recognizable highly stylized conception - YES, the look is Spaghetti but spaghetti from a classy restaurant, not from a working man's osteria
Fluid - Not sure what this means, but there are numerous very long-held shots and static camera positions, so I guess not fluid.
violent - Not particularly for a western. Average body count
minimalist cinematography - HELL NO!

It looks like a revenge western, but the last word is not with Bronson. He disappears into the dust of history along with Robards and Fonda. The final shot with confirmatory and (to me) moving music, is of the unstoppable advance of corporate capitalism (the railway) and of Cardinale's compassion for the (mostly non-white) workers. She understands how the world is changing, as does Morton the rail baron. They probably took classes in dialectical materialism back East.

The Mystical Western
Dead Man (1995) Jim Jarmusch

The Anti-Racist Western
All of them these days, but some made it the main theme.

The Anti-Colonial Western
Numerous depicting the genocide of Native Americans
Also: The Proposition (2005) John Hillcoat

Too much overlap between the previous two to call them separate categories

The Road Movie Western
OK, I am cheating here. This is not a separate genre but a hybrid of two established genres.  But there are an awful lot of them, which is unsurprising since the history of the West is that of people driven on a quest. The criterion of a Road Movie is that at least one of the protagonists experiences a change of heart, or spiritual or psychological change as a result of the journey. An interesting recent one which seems to have slipped past unnoticed, despite starring the currently fashionable Michael Fassbender and Ben Mendelsohn, is Slow West (2015). It is also a Revenge Western and an Ecological Western. 

The Social Realist Western
Tommy Lee Jones seems to make westerns which utilize the traditional theme of doing what is right although it is hard, but with painful realism and complexity unlike the mythical world of the traditional western. The Homesman (2014) is a brilliant and much underrated movie. This is what the west was really like. Though it does have one sequence (when the hotel burns) which is straight out of a Clint Eastwood "mystical" western, or even out of David Lynch, it so surreal. And the last shots are lyrical. It is also a Road Movie, by the way, with the getting of wisdom through a journey.

The film also has an unusual plot structure, but I will start a separate thread on that.

The Black Comedy Western
There Was a Crooked Man (1970) Joseph L. Mankiewicz
A lot of dry humor and a sly ending where the cleverest crook wins.

The NOT a friggin' Western!
As stated above, the fact they are on horseback and wearing cowboy hats does not make it a western, regardless of the location. These are not westerns, though I have seen them called that:
Hell or High Water (2016) - a crime caper with family problems
Ride With the Devil (1999) - a Civil war movie
Lone Star (1996) - a police investigation with family problems (to put it lightly)
The Last of the Mohicans (2015) - a historical

What about The Hateful Eight (2015) Quentin Tarantino? Well, it is a real hybrid of genres, but more than anything it belongs with the Agatha Christie drawing-room thrillers, where all the suspects are confined to one room and gradually get killed off, finally revealing the killer.

the space western