Obviously, when Latin was used as the primary language of literature, law, and recording, plenty of surnames, or geographically based surnames would have been passed down to modern in Latinized form. Off the top of my head, I think of Duns Scotus, Copernicus, Stradivarius, Mercator, Vesalius, and Hugo Grotius. However, after a certain point in the early modern era, we don't seem to often refer to famous historical figures by their Latinized names anymore. I originally thought this might reflect a shift from Latin to vernacular languages as the primary languages of scholarship, but I'm not sure this is quite right—we know him as Isaac Newton, not Isaacus Newtonius, despite the Principia being in Latin.
However, the practice seems to last longer, and even to the present day in some cases, in the German-speaking parts of Europe and especially in Scandinavia. The Lion of the North is commonly known as Gustavus Adolphus, the Polish-Saxon rulers are called Frederick Augustus I & II. Among scientists: Celsius, Linnaeus And these endings are preserved in ordinary surnames, too. The Dutch have continued to officialy foist such given names as Jacobus, Marinus, and Hendrikus upon their unfortunate progeny, but by and large the descendents of Hugo Grotius probably use "de Groot".* This seems to be less the case farther east: again, quickly off the top of my head I can think of more modern figures like Jean Sibelius, Walter Gropius, Svante Arrhenius, Friedrich Paulus, Gustav Magnus, and a couple of people named Möbius.
Is this an entirely imagined phenomenon, or is there some real basis to it? Or is these remnants of Latinized surnames to be expected? One can imagine that in Romance-speaking countries a formal Latin name could quickly revert to the vernacular equivalent with the decline of Latin as a legal language, without too much friction at all. In Germanic-speaking countries, one could also imagine that this transition would be less subtle. Or were Latinized surnames a signifier of some sort of noble status, a holdover from a time when commoners wouldn't have had surnames at all? I'm also wary, when speaking of Prussian and eastern Germanic surnames, not to include Lithuanian names, which I understand use -ius and -us as native, non-borrowed endings.
*Didi Gregorius, Andreas Cornelius, and Oscar Pistorius seem like prominent exceptions to the de-Latinization of Dutch names
Scandinavia does not have a long tradition of heritable last names (and Iceland never adopted it).The systematic use of patronymics (-son/-sen and -dotter/datter etc names) was adopted in the Middle Ages. (so Viking Age figures like Leif Eriksson are actually after-the-fact constructs that wouldn't have been used at the time, and aren't used in the actual historical source either)
This applied to everybody, even nobility. So when you read medieval Scandinavian history and see something like "Karl Knutsson (Bonde)", the family name is in parentheses. Noble family names themselves were usually just a description of the coat of arms. (e.g. Gyllenstierna - 'golden star' - arms) They did not begin using these family names as surnames until the Renaissance. (in Denmark they passed a law outright forcing them to do so)
Around that time (late 1400s) you also have members of the clergy and academics adopting surnames, which are often latinized forms of something or another. In the Middle Ages, using latinized forms when writing in Latin was the norm, but these were just Latin renderings of their native names - Henrik Karlsson becomes Henricus Caroli. Those were not heritable. Henrik's son would have the surname Henriksson and most likely render it as Henrici in Latin.
But these new heritable surnames that were being adopted after the Renaissance were not latinized forms of existing names, as these people didn't have existing family names. They weren't latinizations of their patronymics either (with inheriting names being a new thing, inheriting a patronymic which thus becomes incorrect was perhaps too far-fetched; it's only in the late 19th and early 20th century that patronymics begin to be inherited rather than new ones formed)
In the Scandinavian tradition they were typically based on the name of the farm or village the family was from. The scientist Arrhenius took their name from the farm Årena, Sibelius from Sibbe. A man from a farm named Högen (the high point) rendered that into Latin celsus (lofty, high, elevated) and derived the name Celsius from it. And so on. Sometimes it was based on other things, like a nickname, like Campanius for someone known as Klockare ("Bellringer") because he was one. (profession-based nicknames were common but seldom become inherited surnames)
So they begin in the 16th century but these names really reach their high point in the 17th century, when it becomes very popular among the clergy. It begins to be considered outdated as one enters the 18th century though. As all things French come into fashion in that century (and then fall from grace in Napoleon's day), people began to adopt the French -in ending (as in the French names Martin, Perrin, Robin, etc).
(So goes the common explanation; another that was pointed out to me when last posted about this is that it may have arisen simply as a clipping of the longer -inus form. I'm not sure these explanations are at odds though; it could have arisen as a clipping but the use cemented by the perception it was trendy and French)
So if you're living in mid-1700s Scandinavia and you just moved from your farm "Dalen" to university and want to adopt a surname, then "Dalenius" old-fashioned and "Dalin" is now the way to go. Another example is the famous astronaut "Buzz" Aldrin, of Swedish ancestry. (For fun I traced his family name back and it was adopted in the mid 1700s, by a smith, not a clergy member, and almost certainly derives from the farm Alderbäcken in Hagfors)
So by the 18th century you begin to see more widespread adoption of heritable family names. Not just -in names but for instance soldier names, which are based off nicknames people had as soldiers; they're usually quite macho (adjectives like "strong", "fast", "dexterous", "willing", "brave" or nouns like "sword", "shield", "dagger" or even "bang" and "gunpowder").
But as said, it wasn't until the 19th and early 20th century that the vast majority of people either invented names (like "Blomkvist") or just began inheriting patronymics. Interestingly, -dotter names began to be perceived as old-fashioned prior to patronymics disappearing, so there were a few decades where women were getting patronymics with -son.
So in the case of Scandinavia (not to say this isn't also true to an extent elsewhere), these 'latinized' names are common simply because they're not latinized forms of a native name, but rather original in their Latin form. The botanist Carl Linnæus is not known as this (merely) because he published under that name; he was the son of Nils Linnæus, who was the son of an Ingemar Bengtsson. In Carl's case though, he was ennobled and then adopted the name [von] Linné (yes that's likely a French-inspired -é no doubt) which is how he's commonly called in Swedish.
It's correct these names were associated with higher status, although there was no law limiting it. Adopting one signaled that one had left the peasantry and entered the estate of burghers or clergy.
With names like Gustavus Adolphus it's different though. That's a matter of there being a custom to use the Latinized form in English for him and a lot of other kings. He did frequently sign his own name with the Latinized form though, but of course the context is often that the document was in Latin as well. Also, until quite recently it was very common that Scandinavian provinces were referred to in English by Latinized forms of the names: Helsingia and Dalacarlia rather than Hälsingland and Dalarna. (but for towns 'Stockholm' and 'Gävle' rather than Holmia and Gevalia)
