Rabbi Yochanan

Yohanan, Yochanan and Johanan are various transliterations to the Latin alphabet of the Hebrew male given name יוֹחָנָן‎ (Yôḥānān), a shortened form of יְהוֹחָנָן‎ (Yəhôḥānān), meaning "Yahweh ".

The name is ancient, recorded as the name of Johanan, high priest of the Second Temple around 400 BCE. It became a very popular Christian given name in reference to either John the Apostle or John the Baptist.

The Hebrew name was adopted as Ἰωάννης (Iōánnēs) in Biblical Greek as the name of both John the Baptist and John the Apostle.

In the Latin Vulgate this was originally adopted as Iohannes (or Johannes – in Latin, J is the same letter as I). The presence of an h, not found in the Greek adaptation, shows awareness of the Hebrew origin. Later editions of the Vulgate, such as the Clementine Vulgate, have Ioannes, however.

...
Wikipedia