[Holy shit, this one turned out LONG. But believe me, this guy deserves it]
So it's a real crime that the next weirdo artuer I'm going to mention isn't mentioned alongside other Eastern European arthouse giants that were his contemporaries, but there are a lot of reasons Andrzej Zulawski was a largely overlooked director until recently. If you know Zulawski for anything, it's probably Possession, his only English language movie, a social/body horror/psychosexual nightmare where Sam Neill crashes a motorcycle into the Berlin Wall and Isabelle Adjiani fucks a Carlos Rimbaldi-designed monster (which, by the way, he created the same year as ET). While all his movies are completely bizarro and worth a look (if you can find them), his 1st 6 features are absolute masterpieces. Zulawski manages to push his actors to a more extreme place than most cinema is willing to go, and the emotional intesity that radiates off the screen as a result of that strikes the viewer like lighting and leaves an indelible mark on the psyche (no trailer sharing this time, because each Zulawski movie has things that would be very hard to explain away at the average workplace).
He started off with The Third Part of the Night, a dreamlike, gruesome noir set in a WWII-era Warsaw ghetto and based on his Father's experiences as a Jew in Nazi Poland. After his family is callously executed by SS officers, a man becomes obssessed with a young mother who's her exact double (played by the same actress); an obsession that sets him on a path to becoming a medical guinea pig infected with diseased fleas and, ultimately, his own doom. Third Part garnered so much international praise that his 2nd feature was immediately approved - The Devil.
The Devil is very, very hard to find, and with good reason. Zulawski had been part of an anti-communist journalism organization that was destroyed by spies from the Polish Government posing as sympathizers and spreading divisive, paranoid rumors to the other members. Zulawski was so incensed at the government's actions that he decided to take the money they'd gave him and make a giant middle finger in movie form. While Devil is obstensibly a fairytale like period piece, it's subtextually a scalding inditement of Communist spycraft tactics. A young nobleman is sprung from jail in 17th Century Poland to find that his father is dead, his sister has married his most despised enemy to survive, and his onetime fiancee is preganant with his best friend's child. From there he descends into violent madness (descents into madness are a big part of the Zulawski aesthetic), spurred on by a demonic figure whose methods just happen to resemble the Polish government's anti-journalism tactics. For example, the Devil hands him a knife, saying that he should never use it, but by all means if he were in the same position he would TOTALLY UNDERSTAND using it to kill everyone that wronged him, not that he should, but it would be TOTALLY UNDERSTANDABLE.
After Zulawski turned in the final cut of the film, the Polish censor board was less than impressed. They informed him he and his wife, Polish ingenue Malagorzata Braunek (the lead actrsss in most of Zulawski's early work), had 48 hours to leave the country or they would be jailed, and Devil wasn't released until a decade later. Zulawski and Braunek landed in France and made L'important c'est d'aimer, a heartwreching drama about love triangles and theater troupes that starred Braunek and Klaus Kinski. Hailed as a masterpiece on the European arthouse circuit, it made Poland reconsider Zulawski's exile.
To lure him back, the Polish government not only promised to make he and his wife full citizens again, they promised to fund any script he came up with next. He came up with what, at the time, was the most expensive movie Poland had ever funded. On The Silver Globe was to be a centuries-spanning sci-fi epic based on a novel written by Zulawski's grandfather. The plot is dense, surreal, and impossible to sumamrize, even moreso because it was never officially finished. 3/4ths of the way through production, government censors realized Zulawski was making yet another anti-Communist movie. They ordered all the negatives, sets, and costumes to be burned and exiled Zulawski and Braunek permanently. 10 years later, Zulawski revealed over the past decade his crew on the film had been smuggling him as much complete footage as they could from Poland to France. Zulawski fills in the gaps by walking around the streets of Paris with a camera and narrating what the viewer would've seen in the finished movie. It ends with with Zulawski filimng himself in a department store window, outlining what would've been the final scene and giving an acidic thanks to the Polish government for creating the cut of the movie he's just shown.
Both getting kicked out of Poland and having her career destroyed for the 2nd time was where Braunek understandably reached a breaking point, and she and Zulawski had a nasty divorce. Zulawski channeled that misery into Possession, which despite all the supernatural (and otherwise) horror is at its core a story about a guy who just does not want to accept that his wife wants to be in love with a better person than him ("Can't you see I despise you?!" Adjiani snarls when Neill grabs ahold of her to keep her from leaving). The first half is tense emotional drama (where half the dialogue was taken from direct transcripts of phone conversations between Zulawski and his wife), but it slowly mutates into metaphorical apocalyptic body horror that would do John Carpenter or David Cronenberg proud.
Having emerged from the dark night of the soul, Zulawski decided to take the piss out of himself and made La Femme Publique, a metatextual satire on himself that features an actress having to contend with a obsessive, sociopathic Polish arthouse director who may actually be a serial murderer. While it definitely works on its own, watching it with the context of the 5 previous movies makes the jokes way funnier (as the director bemons his recent divorce, his producer snorts "Of course she left you! You got her kicked out of her home country and destroyed her career - twice!").
TLDR; All of Zulawski's movies are worth a look, but the first half-dozen are the high watermark of his career.