Well, in that case I'm probably mistaken, because the C's answer regarding last Roman Emperor was Justinian.
Following another clue from the C's:
some "doublets" or better said "multiplets" of particular historical accounts were potentially spotted and presented in "Procopius' Secret History"
thread.
Going back to the C's session with Caesar in 2014 (Year 0), that basically initiated this line of inquiry:
simple math gave that the event that destructed Roman Empire (536 AD in official chronology) happened 157 years after Caesar's birth, which would provisionally put it in the mid 50s AD. That would also mean that there was roughly only a century of real Roman history after Caesar was assassinated, which would not give enough time in the official version even for Nero to rise to the throne.
With all that in mind, it's probably wise to approach finding the resolution of that mess conservatively with the assumption that everything we have been told about Roman history after Caesar's were lies until proven otherwise, especially those historical accounts that came to us in written form. On the other hand, some things surely need to be accounted for, like still existing monuments from that period and inscriptions on them, and existing original busts, portraits, coins and other material artifacts, which might need some creative reinterpretation of their real meanings and what they actually tell us about life in those times.
Regarding the written accounts of the 1st century AD, if we're going to follow C's hints and suggestions, what we have from Tacitus and Suetonius need to be deconstructed to filter out anything of any true value.
It also might be interesting to entertain the possibility that those two could have been the same person in reality, as there are some curious parallels between them. For example, names of both have a similar meaning, (Publius Cornelius) Tacitus standing for 'silent, quiet, without words' and (Gaius Suetonius) Tranquillus means 'quiet, calm, serene'. They were both very good friends with Pliny the Younger, and they both cover Roman history up to and including the reign of Domitian about whom both write after the fact, mainly during the time of emperor Trajan in rather negative light. Then they both report their age with a similar or identical phrase.
Tacitus (
link):
Suetonius (
link):
Turning to their works, regardless of the connection between them, we can find about Suetonius'
Twelve Caesars (
link):
where we see that dating was provided by Lydus during the reign of emperor Justinian (possible Flavian influence), while the oldest manuscript came from Tours which immediately reminds to historical accounts of Gregory of Tours (Carolingian influence).
In the section Influence we see the Carolingian link in our face:
while when checking
Historia Augusta (
link):
we additionally see that Suetonius'
Twelve Caesars basically present either a template or an account for all Roman emperors til the time of Diocletian, except for Nerva and Trajan, two emperors immediately following Domitian, during who's time Suetonius allegedly had written his work. It is maybe indicative to note that basically all emperors from the time of Constantine's predecessor bore regnal title as "Imperator Caesar Flavius <insert the name> Augustus" which might point to Flavian meddling with the records.
And about works of Tacitus (
link):
meaning that we only really have the account about the Year of Four Emperors (69 AD) and shortly after into the Flavian dynasty.
Other Tacitus' historical works were under suspicion already at the time of Voltaire (
link):
The same man also found
Agricola (
link):
Even if we accept the
Annals as real history, basically we only have partial accounts about emperors Tiberius, Claudius and Nero, where first two share the name, Tiberius Claudius Nero, while the last one dropped the 'Tiberius' from his. If you check their statues and busts, rather big likeness between the first two is evident, while face on the statues of older Nero is not far behind.
Could this mean that out of all what we got from
Annals, we in fact have accounts of only one emperor, Tiberius Claudius Nero? Which together with Histories only covered the time period of the reign of one man with the civil war and unrest after his alleged 'assisted' suicide?
Another interesting bit that is kinda suggestive of that direction is the respective years of reign.
Tiberius reigned for 23 years until 37 AD and his age of 77 (according to
Wikipedia). Claudius reigned for 13 years til 54 AD and his age of 63. Nero reigned for 14 years until 68 AD and his age of 30. If we add to Claudius' reign Nero's one, looking at it as of a single man, we get an emperor ruling until he is 77 years old, the same age as Tiberius was when he died. Coincidence? The reign of such an emperor would last 27 years, exactly how long the combined official reign of Flavians Vespasian-Titus-Domitian lasted. Another coincidence?
From the official end of Tiberius in 37 AD until the supposed "536 AD event" in the mid 50s AD, is cca 20 years. Would that be enough for all other things that we still need to account for, like building the Aurelian Walls (
link) for example if they really belong to the Roman era, where blinded Belisarius is said to have been condemned to asking passers-by to "give an
obolus to Belisarius" (
date obolum Belisario), before pardoning him, if he was actually a real historical figure of course? Would it be enough time for everything that is said about the supposed last Roman emperor, Justinian?
I don't know...
Although, seeing that Tiberius Claudius Nero was rather antagonistic towards his (adoptive) step-father Octavian Augustus' posthumous worship, and that Suetonius reported that Tiberius upon coming of age, which should have been during the reign of Augustus which officially started in 27 BC, staged two gladiatorial contests in honor to his father and maternal grandfather, who were stark opponents of Augustus, it seems that what we know about the time period before Tiberius via Suetonius might also be in need of some readjusting.