Gabriel is one of the main archangels in Abrahamic Religions (Judaism, Christianity, Islam. He is one of the most popular with his power and devotion to God. He is usually sent down as a messanger for very special events on Earth. His name means "GOD IS MY STRENGHT".
Appearance in Bible :
Old Testament : Angel Gabriel appears to phrophet Daniel just once. He interprets Danails visions in "Book of Danail". Also in "Book of Ezekiel" he is supposed to be the angel, who will destroy Jerusalem.
(acc. to Jewish Mythology Gabriel brings the "new souls" from the "Tree of life" or Tree of souls, then gives them to another angel -Lailah.
New Testament : Gabriel comes as a sign for "glad tidings" in front of Zachariah & Virgin Marry. He announced the message for the future birth of the prophet John and of Jesus (as well as in Quran). (Luka 1:5-7); (Luka 1:21-25). He present himslef by name, when he delivers the message.
In Christian tradition Gabriel is the angel, responsible for blowing the horn/ trumpet on the Judgment day (for muslims that is angel Israfil -Raphael in Yom il Qiyama)
Islam : Jibrail is the messanger who reveals the Holy Quran to proph. Muhammad in period of 23 years. During that time the prophet saw him 2 time in his full glory. He is named many times in Quran, and there is also "Hadith of Gabriel". Jibrail appears in fron of Virgin Marry in Quran (surah Mariam 19:2/ 19:21)
