The word angel derives from the Greek angelos, which means 'messenger'. Originating in Zoroastrianism they are found mainly in Christian, Judaic and Islamic writings.
For sites dealing with one or more Angels.
The word archangel from Middle English and from Old French is 'archangele' and 'archangelus' from Late Latin. 'Arkhangelos' from Late Greek.

This high-ranking choir comprised of 4, 5, 7 or 9 angels depending on what sources you read. The three commonly accepted Archangels are Michael, Gabriel and Raphael. The others are subject to debate; Uriel, Raguel, Zadkiel, Saraqael, Remiel, Anael, Orfiel, Uzziel, Raziel and Metatron. The Koran only recognized 4 and names two; Djibril (Gabriel) and Michael.

Sites dealing only with one or more of the following angels: Michael, Gabriel, Raphael, Uriel, Ariel, Raguel, Zadkiel, Saraqael, Remiel, Anael, Orfiel, Uzziel, Raziel and Metatron.
Fallen angels are angels who no longer reside with God. Generally the most common of these are Lucifer and the other angels who lost the War in Heaven, however sometimes demons, watchers, grigori, devils and goetics are also included as fallen angels.
For sites dealing with fallen angels in general. Sites for demons should go to Society/Religion_and_Spirituality/Esoteric_and_Occult/Satanism/Demonolatry/Demons/, sites for watchers should go to Society/Religion_and_Spirituality/Spiritual_Beings/Angels/Watchers/.
According to lore there are both 'bad' and 'good' Watchers, however the most famous ones were the two hundred who came to earth and interacted with humankind.

The Watchers were a specific race of divine beings known in Hebrew as 'nun resh ayin' or 'irin' meaning 'those who watch' or 'those who are awake', which is translated into Greek as Egrhgoroi egregoris or grigori, meaning 'watchers'.

Sites dealing with the Watchers or other names they were known by ie (Grigori, Shining Ones etc) are welcome here.