Well, there was Otto Rahn, German medievalist, SS-Obersturmführer, and Grail Hunter for the Nazis. Rahn himself is a rather marginal figure even within Nazi occultism and while commonly held that in the early stages to have been a talented historian, his name as well as his work is mostly remembered because a.) Indiana Jones had a sinister version of him on screen and b.) his work not only kindled interest in Catharism in the 1930s but were very popular among those responsible for the esoteric and non-academic Catharism revival of the 1960/70s, which gave the world the dubious basis for Dan Brown's DaVinci Code. Basically, it was Rahn who invented the connection between the Cathars and the Holy Grail.

Rahn was born in 1904 and studied Law, Literature and Philology in Giessen and Heidelberg. Despite there being some confusion about whether he actually finished his studies, it is certain that by 1928 he had developed an intense interest in the Cathars, an alleged Christian dualist sect in the South of France, and the Albigensians Crusade, which destroyed the Cathars in the 13th century. Developing a close relationship with French Mystic Antonin Gadal, it was during these travels that Rahn developed his theory of the Grail and the Cathars:

Because, drawing on dubious sources – as is the history of Cathars in general as this post and this post demonstrate – there was the theory among Rahn and people like him that the Cathars had hidden some kind of important treasure. Because Rahn had read the poetic Parzival Saga of Wolfram von Eschenbach, he became convinced that the Grail Castle mentioned in Parzival was actually the Cathar Castle at Montségur, which was the last one to fall during the Albigensians Crusade. Rahn's evidence for this was that in Parzival the Grail castle was called Munsalvaesche, which Rahn took to mean Montségur. And so, by virtue of a questionable etymological connection was born the theory that Cathars had hidden the grail from the Church and had thus been destroyed for this.

Over the next couple of years, Rahn traveled Southern France and the ruins of Cathar castles and so forth to search for the Grail; a search that was abruptly ended when he was sued for being out of money and accused by French authorities of spying for the Germans. By this time, he had also become very friendly with the SS and Himmler in Germany. Himmler, who was particularly interested in medieval myth and legend to construct from them a "Germanic" religion rivaling "Jewish" Christendom, took it upon himself to further help Rahn out.

Rahn, who with the help of Himmler had published his bog book Crusade Against the Grail: The Struggle between the Cathars, the Templars, and the Church of Rome in 1934, would go on to join the SS and develop his theories further: According to him, the Cathars not only held the Grail, but the mixture of medieval heresy, grail legend, and the suppression of the Cathars in a crusade to him formed a new picture. Because of the alleged connection to Eschenbach's Parzival, Rahn posited that the Cathars were not a Christian Sect but in reality had been a Gnostic religion of Aryan-Germanic origin representing the "original" Germanic ur-religion, which was violently suppressed by the Catholic Church in service of the Jews. He went on to travel again to France, Italy, and even Iceland because to him it became clear the Cathars, the Holy Grail, the mysitcal island of Thule so popular among German occultists like Himmler, and even the Tibetan Buddhists legend of Shambala were all connected (Cathars, in his opinion being "the Buddhists of Europe"). He also further connected this with the World Ice Theory of Hannes Hörbinger and other, similar, BS theories.

While Rahn's hunt for the Grail was – obviously – not successful, his books Crusade and Luzifers Hofgesind, eine Reise zu den guten Geistern Europas, both of which were barely veiled SS and Nazi Germania propaganda were hugely popular among certain esoteric and mystically inclined people, not the least Heinrich Himmler.

But while until 1938 Himmler was a huge fan of Rahn and financial backer for his hunt for the grail, in 1938 Rahn was transferred away from his research and had to perform guard duties in the Buchenwald and Dachau Concentration Camps for four months (it is speculated that this might be related to his alcoholism), after which he left the SS (allegedly because of homosexual leanings). In March 1939 a few days before his planned wedding, where Himmler would have been an honor guest, Rahn died hiking in the Tyrolean mountains. Some write he slipped and then froze while hiking, others allege he committed suicide, while still others want to see a more sinister conspiracy behind Rahn's death.

Whatever it was, Rahn's dubious theories live – undeservedly – on through all the dubious literature on the Cathars and the Grail and while his Grail hunt was less spectacular than in the Indiana Jones movies – most of what he did was explore caves and spend time in dusty archives –, he is indeed one of the most recent people to have embarked on a Grail quest.

Sources:

• Nicholas Goodrick-Clarke: The Occult Roots of Nazism: Secret Aryan Cults and Their Influence on Nazi Ideology: The Ariosophists of Austria and Germany, 1890-1935, 1985.

Heinrich Himmler, the infamous head of the SS, was a firm believer in the existence of ancient relics that had an immense power. While it is Hitler who is often portrayed as being "obsessed with the occult" (to quote Raiders of the Lost Ark), it was Himmler who in reality subscribed to all sorts of supernatural theories (see Commiespaceinvader's post in this thread for his support of Otto Rahn). Himmler believed that Mjölnir, the hammer of Thor, the god of thunder from Norse mythology, was an ancient electrical weapon. He believed that if this weapon was found by the Ahnenerbe (the Nazi German institution responsible for research and retrieval of history of the "ancient Aryan race") and its secrets uncovered, perhaps German scientists could turn ancient Norse knowledge into Wunderwaffen, being able to knock out tank divisions and entire armies.

Our source for this belief is a letter that Himmler sent to Ahnenerbe, requesting a search for evidence of Thor's hammer. This letter, dated May 28 1940, to the head of the Ahnenerbe, Walter Wüst gives straight-forward instructions:

Have the following researched: Find all places in the northern Germanic Aryan cultural world where an understanding of the lightning bolt, the thunderbolt, Thor's hammer, or the flying or thrown hammer exists, in addition to all the sculptures of the god depicted with a small hand axe emitting lightning. Please collect all of the pictorial, sculptural, written and mythological evidence of this. I am convinced that this is not based on natural thunder and lightning, but rather that it is an early, highly developed form of war weapon of our forefathers, which was only, of course, possessed by the Aesir, the gods, and that it implies an unheard of knowledge of electricity.

Whether or not these instructions were followed has been lost to history.

Source:

Heinrich Himmler: A Life by Peter Longerich (2011, Oxford University Press)

Perhaps also worth mentioning is the strange character of Brigadeführer Karl Maria Wiligut (a.k.a. Lobesam, Jarl Widar, Karl Maria Weisthor), “the best known esotericist to have had an official rank in the SS and to have produced esoteric work for Reichsführer‐SS Heinrich Himmler” [1]. “Despite Wiligut’s history of illness [megalomania and schizophrenia], Himmler was more than willing to accept his delusions as fact. Wiligut’s ‘ancestral memory’ promised to open a door into German prehistory, and so it was that he was not only welcomed into the SS..., but also appointed head of the Department for Pre- and Early History within Darré’s Race and Settlement office. Relations between Himmler and Wiligut were warm. It was Wiligut who designed the death’s-head ring (the Totenkopfring) worn by members of the SS” [1].

Wiligut--“an eternally obscure man” [1]--was apparently convinced, after consulting runes and other signs, that he himself was the secret king of Germany as heir of the Ueiskuning [holy clan]. “Wiligut was a mercurial character who fully believed in the reality of a lost Atlantean continent that had been the birthplace of the Aryan race. He interpreted the crystal skulls [“discovered” by Mitchell-Hedges at Lubaantun in 1927] as the work of Atlantean craftsmen, with the objects designed for use by priests in their pagan ceremonies” [2]. He also composed strange chants in combinations of modern German, High Old German, Old Norse, Gothic, intending for them “to awaken ancestral memory and facilitate the breakthrough of the Irminist faith” [1].

You might also consider the search for lands. Himmler was fascinated by Iceland as the possible Aryan ancestral homeland of Thule, the land of Ultima Thula, as described by Pytheas in the 4th-century B.C. Thus Himmler seemed to believe that the origins of the Aryan race lie in certain Icelandic and Germanic sagas and myths, like the Eddas and The Nibelungenlied. “Iceland, like Tibet, was considered a holy land and so within the Ahnenerbe an Institute was established to study the Eddas” [2].

Believe it or not, such legends and myths held enormous intrigue for even the Führer himself. In Jan. 1942, Hitler remarked: “Legend cannot be extracted from the void, it couldn’t be a purely gratuitous figment. Nothing prevents us from supposing, and I believe, even that it would be to our interest to do so, that mythology is a reflection of things that have existed and of which humanity has retained a vague memory” [3].

Sources:

[1] The Secret King: Karl Maria Wiligut: Himmler's Lord of the Runes. Translated and introduced by Stephen E. Flowers; Edited by Michael Moynihan (Waterbury Center, Vt.: Dominion Press, 2001).

[2] Barrowclough, David. Digging for Hitler: The Nazi Archaeologists Search for an Aryan Past. (Stroud, U.K.: Fonthill Media, 2016).

[3] Hitler, A., Hitler’s Table Talk 1941-1944 (Oxford: OUP, 1988).

Nazis not only looked for mythological artifacts; they found them, modified them to suit their purposes, and ultimately destroyed objects of legitimate German cultural heritage.

The thing to understand about Nazi archaeology is that it was less eager to investigate the past than it was to restore ur-Germania, or the pre-Christian society of noble savages depicted in documents like the Germania of the Roman historian Tacitus. (Tacitus was not doing ethnography, but was interested in moralizing to an Italian readership. He assigned classical Roman virtues like thrift and chastity to the Germani and argued that Romans had abandoned these. He probably did not ever set foot in Gaul, and his primary audience certainly never had.) To recapture the ur-German spirit that had been replaced with Romanization and Christianity, Nazis pursued literary artifacts (like manuscripts of the Germania), actual artifacts (as u/commiespaceinvader has illustrated), artistic motifs (such as the runic lettering of the SS logo or the Othila rune on some white identity flags), and (the focus of this post and the chapter it's based on) significant sites.

The destruction of the church of St. Servatius in Quedlinburg is especially illustrative. The remains of Henry the Fowler--a 10th century Saxon duke and king of East Francia--were said to be deposited on the grounds of the church, though of course by the 1930s the location was not evident and claim was not especially falsifiable. Henry was regarded in the broader ur-Germania discourse to be the king of the "First Reich." Also arch-propagandist Heinrich Himmler uh thought that he was the reincarnation of Heinrich (the Fowler).

Christianity in Himmler's mind was an imported religion (started by a Jew!) and therefore not Germanic. It was an insult to have the tomb of such an important German Emperor in a Christian space. Furthermore, the Quedlinburg church was in the Gothic style--i.e. flowy and ornate, with lots of textural interplay. It was also a Lutheran Church, which meant that certain distinctive pieces with liturgical and artistic significant dominated the space of the church--an ornate lectern in this case, among other things.

In order to Nazify the space, the Lutheran elements were removed. (Martin Luther was actually a citizen of the Holy Roman Empire and thus this move negated a movement of "German" origin and profound global significance.) The Gothic elements were replaced or papered over to make the Church look more like the earlier Romanesque style (which you'll note is named after a place other than Germany). Electric lights were removed and replaced with candles to make the whole thing seem more old-timey and medieval... but also the benches were replaced with metal folding chairs because they are evidence of mechanized progress and they were more cost-effective (because they were made by non-German slaves). Also, they couldn't find Henry's body, but then the SS found one just in time, which is to say that they interred some guy (at best).

So Himmler sought out a tomb for a forebear (of both Hitler and himself). He found one and didn't like the narrative it told, so he changed the space to fit his narrative. The resulting space is less German, less medieval, and incoherent visually, architecturally, and temporally. And built to house the corpse of some random guy or whatever they came up with on short notice. This was the SS's shrine to the emperor of the First Reich (who was, I remind you, the king of East Francia). They spent an enormous amount of manpower to mangle a medieval Church during a war they were losing to make it look like less of a medieval church in order to honor a medieval guy who was not German to bring glory to Germany.

The way Himmler (and others) used the middle ages has an important lesson for historians about how bad actors can weaponize the past. When someone lapses from medieval history to medievalism, they get to say basically whatever they want, because it will feel medieval. Some scholars (in this volume, Helen Young) talk about a dichotomy between accuracy and authenticity. Accurate history describes what happened in the past, while authentic history accords with our biases and internalized narratives of how the past should have looked. Nazis had much more luck making and weaponizing authentic artifacts than they did finding maps to the Holy Grail on rune stones.

(This is in large part adapted from William Diebold's essay "The Nazi Middle Ages" in Andrew Albin et al., Whose Middle Ages? Teachable Moments for an Ill-Used Past (Fordham 2019) for which this is I think we can all agree highly relevant guerrilla marketing; as always someone hit me up if this is unacceptable. For more on Tacitus, Christopher Krebs, A Most Dangerous Book: Tacitus's Germania from the Roman Empire to the Third Reich (W. W. Norton 2011) talks some about reception.)