Angel

Season 1, Episode 9: Hero
Aired: November 30, 1999
Character: Scourge Commander Trask

While Doyle is away, Cordelia learns of his true identity. Meanwhile, on the inside, Angel learns the strategy to eliminate the half-demon breed population: The Scourge have built a machine whose rays can wipe out any human within a 1/4 mile radius. Angel soon escapes the Scourge and goes to the ship to warn Doyle and Cordelia. He is followed by the soldiers, who place the deadly machine on the ship. With the lives of dozens in jeopardy, Angel and Doyle realize that one of them will have to die in order to disconnect the beams. Though Angel protests, Doyle decides to make the sacrifice. He engages Cordelia in a passionate embrace, then meets the machine. He successfully disconnects it, then dies. (Original Source)

Quotes:

Scourge demon: ''Welcome to a cleaner world. Soon only the pure will be left standing.''
Angel: ''Actually, pure boy, you'll be on your ass.''

Season 1, Episode 14: I've Got You Under My Skin
Aired: February 15, 2000
Character: Ethros Demon

Meanwhile, to show their undying gratitude for Angel's bravery, the family invites him over for dinner the following evening. Wesley informs Angel about the demon presence and the next day, they create a brownie recipe that will reveal the demon's presence. During desert, Ryan puts on a demon face and Angel brings the family AI to exorcize it. While Cordy stays with the family, Wesley and Angel go to the local church to find the priest to exorcize the demon, but they soon learn from the nun that the priest died six months earlier.

Wesley decides he will perform the exorcism and begins the ritual. The strength of the Ethros demon is such that he will most likely kill whomever is performing the exorcism because of its need to inhabit another body, so Cordelia travels into town to purchase a box to contain it. However, the box is too small, and the Ethros demon escapes after its expulsion. Angel and Wesley track him and kill him, but not before learning Ryan was evil before the demon ever entered his soul. They go to the house and rescue Stephanie, Ryan's sister, from a fire he had started. Ryan is taken into police and social services custody, and the family thanks Angel for his work.(Original Source)

Quotes:

Ethros: “I am Ethros. I corrupted the spirits of men before they had speech to name me. - The child was but the last among tens of thousands, one more pure heart to corrupt, one more soul to suck dry.”
Wesley: “Well, chalk up one exciting failure. You didn’t get that boy’s soul.”
Ethros: “Hmpf, what soul?”

Ethros: ''Do you know what the most frightening thing in the world is? Nothing! That's what I found in the boy. No conscience, no fear, no humanity, just a black void. I couldn't control him. I couldn't get out. I never even manifested until you brought me forth. I just sat there and watched as he destroyed everything around him. Not from a belief in evil, not for any reason at all... That boy's mind was the blackest hell I've ever known...When he slept, I could whisper in him. I tried to get him to end his life, even if it meant ending mine... I had given up hope. I know you bring death. I do not fear it. The only thing I have ever feared is in that house.'' (Click here to listen.)

Misc.

Season 1 of Angel is available on DVD at Amazon, Amazon.uk and your local retail store. TV has not aired repeats of the first season in a long while, so this may be your best shot at seeing Anthony work his magic.