Holy One

Definition:

The term "Holy One" is a title in the Bible that almost always refers to God.

In the Old Testament, this title often occurs in the phrase "Holy One of Israel."
In the New Testament, Jesus is also referred to as the "Holy One."
The term "holy one" is sometimes used in the Bible to refer to an angel.

The literal term is, "the Holy" (with "One" being implied.) Many languages (like English) will translate this with the implied noun included (such as "One" or "God").
This term could also be translated as, "God, who is holy" or "the Set Apart One."
The phrase, "the Holy One of Israel" could be translated as, "the Holy God whom Israel worships" or "Holy One who rules Israel."
It is best to translate this term using the same word or phrase that is used to translate "holy."