The animated series Avatar is about the world's power that for long was divided over four nations: Earth, Fire, Water and Air. Eventually the world fell out of balance and there was only one Avatar who could save it: Aang.
S1 E1: The Boy in the Iceberg
S1 E2: The Avatar Returns
S1 E3: The Southern Air Temple
S1 E4: The Warriors of Kyoshi
S1 E5: The King of Omashu
S1 E6: Imprisoned
S1 E7: The Spirit World [Winter Solstice Part 1]
S1 E8: Avatar Roku [Winter Solstice Part 2]
S1 E9: The Waterbending Scroll
S1 E10: Jet
S1 E11: The Great Divide
S1 E12: The Storm
S1 E13: The Blue Spirit
S1 E14: The Fortuneteller
S1 E15: Bato of the Water Tribe
S1 E16: The Deserter
S1 E17: The Northern Air Temple
S1 E18: The Waterbending Master
S1 E19: The Siege of the North, Pt. 1
S1 E20: The Siege of the North, Pt. 2
S1 E34: City of Walls and Secrets
S1 E35: The Tales of Ba Sing Se
S1 E36: Appa's Lost Days
S1 E37: Lake Laogai
S1 E38: The Earth King
S1 E39: The Guru
S1 E40: The Crossroads of Destiny
S1 E41: The Awakening
S1 E42: The Headband
S1 E43: The Painted Lady
S1 E44: Sokka's Master
S1 E45: The Beach
S1 E46: The Avatar and the Firelord
S1 E47: The Runaway
S1 E48: The Puppetmaster
S1 E49: Nightmares and Daydreams
S1 E50: The Day of Black Sun, Part 1: The Invasion
S1 E51: The Day of Black Sun, Part 2: The Eclipse
S1 E52: The Western Air Temple
S1 E53: The Firebending Masters
S1 E54: The Boiling Rock, Part 1
S1 E55: The Boiling Rock, Part 2
S1 E56: The Southern Raiders
S1 E57: The Ember Island Players
S1 E58: Sozin's Comet, Part 1: The Phoenix King
S1 E59: Sozin's Comet, Part 2: The Old Masters
S1 E60: Sozin's Comet, Part 3: Into The Inferno
S1 E61: Sozin's Comet, Part 4: Avatar Aang
S2 E21: The Avatar State
S2 E22: The Cave of Two Lovers
S2 E23: Return to Omashu
S2 E24: The Swamp
S2 E25: Avatar Day
S2 E26: The Blind Bandit
S2 E27: Zuko Alone
S2 E28: The Chase
S2 E29: Bitter Work
S2 E30: The Library
S2 E31: The Desert
S2 E32: The Serpent's Pass
S2 E33: The Drill