This is by no means a complete list, but here are just some of the more notable retellings of Trojan origin myths:

400s BCE: Herodotus states in his Histories (Book IV, ch. 191) that the Lybians claim descent from the Trojans.

400s BCE: Thucydides claims in the History of the Peloponnesian War that the Elymians of Sicily are descended from a group of fugitives of the Trojan war.

20 BCE: Virgil writes the Aeneid, which was based on a foundation myth that already existed at that time in Rome, but thereby created the most popular and spread version of the Aeneas myth of a Trojan founding of Rome. It would set the stage for centuries to come by its association with Rome and also largely shaped the medieval perception of the Trojan war until the rediscovery of Homer's works in the 14th century. It also lead to claims that Antenor had founded Venice and/or Padua, and this ancestry continued to be claimed by the inhabitants of those places in the Middle Ages.

60 CE: Lucan's Pharsalia states the Celtic Arverni of Gaul claimed to be descendants of Trojans and brothers of the Romans.

660: Fredegar's Historia Francorum claims Francius, brother of Aeneas founded a powerful kingdom between the Rhine and Danube, and becomes the progenitor of the Franks

727: The Liber Historiae Francorum elaborates further on a variant of this story, the Merovingian dynasty now being ancestors of Antenor and Priam too.

1000: Dudo of Saint-Quentin's Historia Normannorum equates the Dacians and Danes, and claims they're descendants of Antenor. Thus giving a Trojan descent to the Normans.

You are here --> 1136: Geoffrey of Monmouth's Historia Regum Britanniae traces the British origins to Brutus, a great-grandson of Aeneas.

1180: Benoît (de Sainte-Maure) Chronique des ducs de Normandie repeats the Trojan origin of the Normans. Rigord elaborates on the myth in his own version around the same time.

1230: Snorri Sturluson in Iceland, documenter of much of what's known of Norse mythology, equates Hector and Thor, Loki and Ulysses, and the humans on which the Norse gods were based ; Odin, Thor, Frigg, Freyr etc were a line of kings descended from Priam of the Trojans who had been posthumously elevated to god status. Priam in turn was a descendant of Jupiter and others Roman gods. Hence the Scandinavian and Anglo-Saxon royal lineages stemmed from this line (as did Snorri's own family). Thus not only only are the Norse brothers of the Romans, but their gods are of the same family as the Roman ones too.

1250: Philippe Mouskes' Chronique rimée repeats the Trojan origins of the French. And in the same period the Grandes Chroniques de France are written, including the Trojan origin into the 'official' history.

1300s: Jacques de Guyse from Hainaut in present-day Belgium chronicles his regions history in Annales Historiae Illustrium Principum Hannoniae. Claiming that around 1000 years BCE the Phrygian prince Bavo, descended from Priam founded the city of Belgis, from whence the Belgae came eventually. Thus giving the Belgians a Trojan origin.

None of these stories are thought to have any credibility at all. They're based off an event that already in the earliest cases was many centuries before that time. Events which we know from the Iliad and Odyssey were already heavily mythologized long before these origin stories. There is no real possibility Geoffrey of Monmouth would've been the first to record an oral history that dated back 2,000 years before his time, rather than that he was participating in an ancient historiographic trend that'd become particularly popular in his era due to the medieval exaltation of Rome and general interest in "The Matter of Troy" as it was known in that era.

u/Platypuskeeper already listed several claims of Trojan descent in Antiquity and Middle-Ages and pointed how it was a general historiographical trend but I think it's worth pointing how it wasn't necessarily made randomly and highlights the relationsip between ancient Mediterranean peoples and their trade or political partners before it was largely borrowed by early medieval chroniclers.

When Greeks contacted western Mediterranean peoples, both because of their need to establish and explain relationships, both to understand social and cultural similarities they felt existed between Barbarians and either them or their homeric ancestors, it was explained these peoples were related to ancient Greek history trough a "kinship diplomacy" : as such, Herakles became a founding figure for Gauls as well the progenitor of their kings due to his journey trough the land during his works (along the Via Heracea), Barbarians peoples were attributed eponymous founder (Illyrios, Arvernos, Celtos, etc.) themselves descendants from gods or sons of heroes that founded cities in Hellas, and of course considering these peoples as descending from Trojan exiles.

As explaining and justifying relationship between Greeks and Barbarians trough ancient kinship proved popular and lasting among the latter as well (Hercules being a largely present figure in Roman Gaul), it was carried over by Romans, themselves understanding their political and cultural origin as "Trojans" largely used it as a kinship device : acknowledging peoples as Aedui (or, at the contrary, not acknowledging Arverni) was both a way to include Barbarians within their own political sphere and understanding, but also integrate themselves into native own cultural sphere and understanding.

By the Late Antiquity, this was a basis of ethnogenesis as it was contemporaneously understood. Acknowledging Barbarians as they entered in less unequal relationship with the Empire, as they obviously were more or less importantly tied culturally or politically to Romans, led to acknowledging them as sort of kin, made especially more pressing and easier due to the lack of ancient history of the recently founded coalitions of Franks, Goths, Picts, etc. out of various groups and tribes in the IInd to IVth century. This validation of these peoples, as political entities, was further continued in the Early Middle-Ages, trough "national chronicles", so to say, that borrowed heavily on Virgil, Tacitus and the Bible into making an "origin story" that was to demonstrate that Goths, Franks and Anglo-Saxons did have a prestigious history, and thus were a real people contrary to the Roman view on Barbarians as living in a perpetual present.

In some case, for instance in Gaul, a double Trojan mythos allowed to introduce provincial peoples (Gauls) and Barbarians (Franks) as particularly kin and therefore naturally forming an union.

When Geoffrey of Monmouth relates the tale of Brutus of Troy as the founding figure of Britons, he mostly set himself into a long established tradition; not inventing it himself (Nennius' History of the Brittons already mentions it in passing, possibly out of an earlier narrative from Roman times trough Brito-Roman tradition), although largely expanding on it, but by hijacking the Brito-Roman and Welsh narrative into a Norman one in order to deligitimize Saxon rule; rather than just making a random claim.

Overall, Trojan origin stories are largely a device of "diplomatic kinship" and self-legitimization of identity by both Greeks, then Romans, and Barbarians whom Roman influence set as a master device into late ancient and medieval ethnogenesis.

- Origines des peuples. Les récits du Haut Moyen Âge occidental (550-850); Magali Courmet; 2007

- The Conquest of the Past in The History of the Kings of Britain; Michael Faeltra; 2007