His full name was Rav Avraham Yitzchak Kook tz"l. He lived in Israel before the establishment of the State.
Rav Kook is known as one of the leading thinkers of the Religious Zionist Movement. He was the first Ashkenazi Chief Rabbi of the British Mandatory Palestine and a famous Rabbi, Kabbalist and a renowned Torah scholar.
His ideology holds that establishing the State of Israel has religious significance in that it serves as the beginning of the process of redemption. Religious Zionists see the state of Israel as the fulfillment of the words of the prophets.
He is also known for founding the Mercaz HaRav Yeshiva.