Ezekiel 1:10, 15

Regarding the form and appearance of their faces: they [each] had the face of a man [in front], and each had the face of a lion on the right side, and the face of an ox on the left side; all four also had the face of an eagle [at the back of their heads]. [Rev 4:7]

Now as I looked at the living beings, I saw one wheel on the ground beside the living beings, for each of the four of them.