Unnamed Humans (distant past)

Multiple realities
(covers information from several alternate timelines)

List of unnamed Humans from past eras.

Arab prince and subjects

Sometime in Earth's distant past, it was said that an Arab prince coined the proverb "the enemy of my enemy is my friend", only to be betrayed and decapitated by his own subjects. Spock mentioned this in 2258 of the alternate reality when James T. Kirk suggested they work with Khan Noonien Singh, citing that saying. (Star Trek Into Darkness)

These characters were only mentioned in dialogue.

Explorers

A group of explorers was known to have explored Earth's bodies of water in a primitive sailing ship. (I AM ERROR opening credits)

According to StarTrek.com, these individuals were ancient Polynesians. [1]^(X)

Henry VIII's huntsmen

During Earth's ancient past, King Henry VIII reportedly preferred the company of his huntsmen to Anne Boleyn's, much to her dismay.

In 2367, Data related this to Jenna D'Sora when discussing the subject of lovers not taking the time to spend time with those they loved. (TNG: "In Theory")

These huntsmen were only mentioned in dialogue.

Inheritor

A vision of this inheritor, an ancient Human who received certain gifts from visiting Sky Spirits, kept flashing in Chakotay's memory while visiting the Sky Spirits' homeworld in 2372. This was possible because memory of the event was one of the gifts. (VOY: "Tattoo")

This inheritor was portrayed by an unknown actor.

Irish kings

According to Spock, Kevin Riley imagined himself to be the descendant of Irish kings, a belief which manifested during Riley's 2266 bout of polywater intoxication. (TOS: "The Naked Time")

These kings were only mentioned in dialogue.
The individuals intended could be any of the kings listed here, including Brian Boru and/or the King of Leinster.

Minicoy ambassador

This ambassador of Minicoy was known for his meaningless speeches.

In 2370, Benjamin Sisko mentioned him to Jaro Essa. According to Sisko, the ambassador "used to bluster, exaggerate, and dissemble to get what he wanted. Not at all like you or me. He was a bag of hot air and everyone recognized him for what he was." (DS9: "The Circle")

This ambassador was only mentioned in dialogue.

Murdered prostitutes

Several prostitutes were murdered during Isaac Newton's lifetime.

According to Q, had fellow Q Quinn not caused the apple to fall on Newton's head, he would have died in a Liverpool debtor's prison and have been a suspect in the murders of these people. Q named this, among other occurrences, as examples of how Quinn affected Earth history in a monumental way, and therefore should continue to live, not commit suicide as he wished to in 2372. (VOY: "Death Wish")

This prostitutes was only mentioned in dialogue.

Sage and skeptic

According to Tristan Adams, James T. Kirk's questioning nature regarding the neural neutralizer reminded him of "the ancient skeptic who demanded of the wise old sage to be taught all the world's wisdom while standing on one foot." (TOS: "Dagger of the Mind")

These characters were only mentioned in dialogue.

Seven's ancestors, et al.

These ancestors of Gary Seven, Agent 201, Agent 347 and others were taken from Earth around 3000 BC, by an unknown alien species, who raised these Humans to be the forebears of a pool of genetically-perfect Earth operatives, active during the 20th century. (TOS: "Assignment: Earth")

These forebearers were only mentioned in dialogue.