Of course over the series he starts to open up more and become a main character, so much that his godly demeanor fades and he feels more like a normal person rather than an angel, but the initial introduction of Castiel, with his deep voice and powers, is something to be marveled.
It will always be an episode that will live in infamy in the series, which is why my number one pick ties in closely with this.
What makes this episode even better is the difference we see in Castiel.
Often regarded as one of the best Supernatural episodes out there, “Lazarus Rising” introduces one of the series most beloved characters – Castiel, an angel of the Lord who is responsible for saving Dean Winchester from hell.