Mika'il is an angel mentioned in the Islamic scriptures. He is in charge of bringing the rain whenever Allah commands Him to do so. Other religions called his as Michael.
Whoever is an enemy to Allah and His angels and His messengers and Gabriel and Michael - then indeed, Allah is an enemy to the disbelievers. (Quran Surah 2:98)
The angels are not partners, associates, or rivals with Allah, nor are they His children; but one must still respect and love them. Allahsays: "And they say: ‘The Most Beneficent (Allah) has begotten a child [from the angels].’ Far removed is He from every imperfection! They (the angels) are but honored slaves. They speak not until He has spoken, and [then] they act on His Command." (Quran Surah 21:26-27)
They spend their time worshipping and obeying Allah, glorifying Him and praising Him. Allah says: "They (i.e. the angels) glorify His praises night and day, (and) without slackening (to do so)." (Quran Surah 21:20)
Narrated Samura: The Prophet (ﷺ) said, "Last night I saw (in a dream) two men coming to me. One of them said, "The person who kindles the fire is Malik, the gate-keeper of the (Hell) Fire, and I am Jibreel, and this is Mikhail." Sahih al-Bukhari 3236 
A Muslim must believe specifically in all the angels named and/or described in the Qur'an and the ahadith: