The role of the Kohein Gadol on Yom Kippur clearly takes center stage. The burden of the entire nation rests on the shoulders of the כהן גדול.
He enters the Holy of Holies several times during the day, seeking atonement for all of the Jewish people. A rope is placed around him in the event that he is proven to be unworthy. If he is unworthy, he dies and is pulled out by the rope.
Seven days before Yom Kippur, he leaves his home and makes preparations for the Temple service. He is not permitted to sleep the entire night of Yom Kippur.
He makes three confessions on one bull and two goats, with one of the goats, the שעיר לעזאזל, the scape goat, being thrown of a cliff. He confesses for his family, all of the Kohanim, and the entire Jewish nation.
The people witnessing these confessions are awe struck as he utters Hashem's holy name. They fall on their faces in prayer.
When the Kohein Gadol succeeds in his mission, his face radiates with incredible holiness. As the Machzor states, "Happy is the one who merited seeing the face of the Kohein Gadol on Yom Kippur. How sad are we that we have not witnessed it."
May the Temple be rebuilt speedily in our time.