Since the "wise king" in the Mar bar Serapion is not named some historians have tried to work out who he was. From the text we are looking for a Jewish man who was killed by Jews. This has to of taken place before Jerusalem fell and before the Jews lived scattered all over the place, this could be either in 586 BC or 70 AD. Most people think it is more likely a reference to the 70 AD event. The wise king teachings also lived on after he died and could not be silenced.
Some people point to the writings of the Essenes, a Jewish sect from around 200 BC to 100 AD, which talks about a Teacher of Righteousness as been the same "wise king". The problem with this Teacher of Righteousness reference as been the same person as our "wise king" is that it is also just as vague. Those who point to this reference to avoid a Jesus link are in trouble as he is listed in the possible suspects for this role as well. The following people have been suggested as the Teacher or Righteousness are Onias III, Mattathias, Judah the Essene, Zadok, Menahem, Jesus, John the Baptist and James the Just. To make this side tracked even more confusing there is even an argument that the Teacher of Righteousness wasn't a person, but an office, held by the leader or high priest and then passed down to the next guy in line. More information about this side track can be found in this thesis.
So back to this "wise king"... Below is a partial list of suspects (do you know of anyone else who is a strong contender?):
Onias III (198 BC) was a Jewish High Priest was killed by Andronicus (a Jew) causing both Jews and Greeks to mourn the death of him (2 Maccabees 4:33-38). This happened around 270 years before the temple was destroyed.
Mattathias (167 BC) was a Jewish priest who stood up to the Greek King Antiochus IV Epiphanes who sent a commissioner to asked him to make sacrifices to Greek gods. Instead Matthias killed the kings commissioners on the alter. He then rallied some people with him, but later fled. (1 Maccabees 2:17-28) This happened around 240 years before the temple was destroyed.
Judah the Essene (lived under John Hyrcanus who reigned 134 BC-104 BC) was a man "who never missed the truth in his predictions" (Ant 13:311 and War 1:78-80) and was possibly the first leader of the Essenes. This then makes him at least known for his teachings and leadership. I am unsure of when he died but would have been around 130-170 years before the temple fell.
So what about Jesus- does he shape up?