The original Letter of James was written in Greek. In the Greek text of Matthew, Mark, Luke, Acts, 1 Corinthians, Galatians, James, and Jude, the English word "James" is based on the original Greek word Iakobos (Jacob). (The initial "I" in Greek is pronounced in the English transliteration as a "J" -- just as the initial "I" in the Greek name Iesous (Jesus) is pronounced in the English transliteration as a "J.") In the Greek Septuagint Old Testament and in the New Testament, the Hebrew patriarch known in English as "Jacob" is known in the Greek texts as Iakob," which is derived from the Greek word Iakobos.

"James" was not used in the KJV to especially honor King James, though the name "James" was made even more popular because of King James. "James" had already been considered to be the Middle English equivalent of the Greek word Iakobos.

Below is the etimological description from The American Heritage Dictionary of the English Language, Fourth Edition (Houghton Mifflin Company, 2000), which helps to explain the derivation of the name "James."

ETYMOLOGY: Middle English, from Old French, from Late Latin Iacomus, variant of Iacobus...

There is also a useful short history of the name James at http://www.geocities.com/edgarbook/names/j/james.html.

To explore the biblical references to James, the brother of Jesus, see:

http://www.bibletexts.com/terms/jesusfamily.htm

To explore the biblical references to James, one of the twelve disciples of Jesus, see:

http://www.bibletexts.com/glossary/thetwelve.htm