Seraphim

Revelation 4:6-8
6Also in front of the throne there was what looked like a sea of glass, clear as crystal.
In the center, around the throne, were four living creatures, and they were covered with eyes, in front and in back. 7 The first living creature was like a lion, the second was like an ox, the third had a face like a man, the fourth was like a flying eagle. 8 Each of the four living creatures had six wings and was covered with eyes all around, even under its wings. Day and night they never stop saying:

Holy, holy, holy

is the Lord God Almighty,

who was, and is, and is to come.