The list is ordered from the oldest to the most recent announcement made by the Riot staff regarding skin sales.

Pre-Seasons Seasons
Pre-Season One Season One
Pre-Season Two Season Two
Pre-Season Three Season Three
Pre-Season Four Season Four
Pre-Season Five Season Five
Pre-Season Six Season Six
Pre-Season Seven Season Seven
Pre-Season Eight
Early Sales


Period Sales Link
November 13
2015
November 16
2015
NasusSquare Pharaoh Nasus [S|L] - 50% off
TaricSquare Armor of the Fifth Age Taric [S|L] - 50% off
Master YiSquare Ionia Master Yi [S|L] - 50% off
AkaliSquare Silverfang Akali [S|L] - 50% off
[1]
November 17
2015
November 20
2015
EvelynnSquare Shadow Evelynn [S|L] - 50% off
Jarvan IVSquare Dragonslayer Jarvan IV [S|L] - 50% off
AhriSquare Dynasty Ahri [S|L] - 50% off
UrgotSquare Battlecast Urgot [S|L] - 50% off
[2]
November 20
2015
November 23
2015
Lee SinSquare Traditional Lee Sin [S|L] - 50% off
VolibearSquare Northern Storm Volibear [S|L] - 50% off
RenektonSquare Pool Party Renekton [S|L] - 50% off
Kha'ZixSquare Guardian of the Sands Kha'Zix [S|L] - 50% off
[3]
November 24
2015
November 27
2015
YorickSquare Undertaker Yorick [S|L] - 50% off
GravesSquare Mafia Graves [S|L] - 50% off
SejuaniSquare Darkrider Sejuani [S|L] - 50% off
AatroxSquare Mecha Aatrox [S|L] - 50% off
[4]
November 27
2015
November 30
2015
LuxSquare Sorceress Lux [S|L] - 50% off
SivirSquare Bandit Sivir [S|L] - 50% off
NidaleeSquare Headhunter Nidalee [S|L] - 50% off
EliseSquare Death Blossom Elise [S|L] - 50% off
[5]
December 1
2015
December 4
2015
GarenSquare Sanguine Garen [S|L] - 50% off
RammusSquare Chrome Rammus [S|L] - 50% off
Kog'MawSquare Deep Sea Kog'Maw [S|L] - 50% off
ZiggsSquare Pool Party Ziggs [S|L] - 50% off
[6]
December 3
2015
December 7
2015
EzrealSquare Ace of Spades Ezreal [S|L] - 31% off
NasusSquare Archduke Nasus [S|L] - 31% off
VayneSquare Arclight Vayne [S|L] - 23% off
ZileanSquare Blood Moon Zilean [S|L] - 23% off
GalioSquare Debonair Galio [S|L] - 31% off
UdyrSquare Definitely Not Udyr [S|L] - 23% off
BardSquare Elderwood Bard [S|L] - 23% off
JinxSquare Firecracker Jinx [S|L] - 28% off
JayceSquare Forsaken Jayce [S|L] - 28% off
RammusSquare Guardian of the Sands Rammus [S|L] - 23% off
SkarnerSquare Guardian of the Sands Skarner [S|L] - 23% off
XerathSquare Guardian of the Sands Xerath [S|L] - 28% off
AkaliSquare Headhunter Akali [S|L] - 28% off
VarusSquare Heartseeker Varus [S|L] - 28% off
MordekaiserSquare King of Clubs Mordekaiser [S|L] - 31% off
AsheSquare Marauder Ashe [S|L] - 31% off
WarwickSquare Marauder Warwick [S|L] - 31% off
ZiggsSquare Master Arcanist Ziggs [S|L] - 28% off
SorakaSquare Order of the Banana Soraka [S|L] - 31% off
SyndraSquare Queen of Diamonds Syndra [S|L] - 31% off
FiddlesticksSquare Risen Fiddlesticks [S|L] - 28% off
EkkoSquare Sandstorm Ekko [S|L] - 23% off
Xin ZhaoSquare Secret Agent Xin Zhao [S|L] - 23% off
LuxSquare Star Guardian Lux [S|L] - 28% off
AmumuSquare Surprise Party Amumu [S|L] - 28% off
AnnieSquare Sweetheart Annie [S|L] - 31% off
NamiSquare Urf the Nami-tee [S|L] - 31% off
NautilusSquare Warden Nautilus [S|L] - 31% off
SivirSquare Warden Sivir [S|L] - 31% off
KatarinaSquare Warring Kingdoms Katarina [S|L] - 23% off
NidaleeSquare Warring Kingdoms Nidalee [S|L] - 23% off
ShacoSquare Wild Card Shaco [S|L] - 31% off
[7]
December 4
2015
December 7
2015
GangplankSquare Minuteman Gangplank [S|L] - 50% off
TwitchSquare Pickpocket Twitch [S|L] - 50% off
SonaSquare Pentakill Sona [S|L] - 50% off
ZileanSquare Shurima Desert Zilean [S|L] - 50% off
[8]
December 8
2015
December 11
2015
AniviaSquare Bird of Prey Anivia [S|L] - 50% off
KayleSquare Battleborn Kayle [S|L] - 50% off
JannaSquare Hextech Janna [S|L] - 50% off
LuluSquare Dragon Trainer Lulu [S|L] - 50% off
[9]
December 11
2015
December 14
2015
AsheSquare Sherwood Forest Ashe [S|L] - 50% off
TrundleSquare Constable Trundle [S|L] - 50% off
MordekaiserSquare Pentakill Mordekaiser [S|L] - 50% off
AnnieSquare Reverse Annie [S|L] - 50% off
[10]
December 14
2015
December 19
2015
2015 All-Star Event Bundles (flexible cost):
1. All-Star 1v1 Champion Bundle - 50% off, RP 2399 (RP 4787 with the champions):
DravenSquare Pool Party Draven [S|L]
LucianSquare Striker Lucian [S|L]
EzrealSquare TPA Ezreal [S|L]
ZedSquare Shockblade Zed [S|L]
Vel'KozSquare Battlecast Vel'Koz [S|L]
2. All-Star Winner's Bundle - 50% off, RP 2699 (RP 5042 with the champions):
LissandraSquare Blade Queen Lissandra [S|L]
EliseSquare Blood Moon Elise [S|L]
ZedSquare SKT T1 Zed [S|L]
KalistaSquare Blood Moon Kalista [S|L]
BlitzcrankSquare iBlitzcrank [S|L]
2. All-Star Playmaker's Bundle - 50% off, RP 2211 (RP 4047 with the champions):
AzirSquare Galactic Azir [S|L]
SivirSquare Warden Sivir [S|L]
GnarSquare Gentleman Gnar [S|L]
JannaSquare Fnatic Janna [S|L]
RivenSquare Battle Bunny Riven [S|L]
[11]
December 15
2015
December 18
2015
OlafSquare Forsaken Olaf [S|L] - 50% off
AmumuSquare Little Knight Amumu [S|L] - 50% off
ZacSquare Special Weapon Zac [S|L] - 50% off
MalphiteSquare Mecha Malphite [S|L] - 50% off
[12]
December 16
2015
December 16
2015
AniviaSquare Noxus Hunter Anivia [S|L] - 50% off
ViktorSquare Prototype Viktor [S|L] - 50% off
TeemoSquare Recon Teemo [S|L] - 50% off
TristanaSquare Firefighter Tristana [S|L] - 50% off
GragasSquare Scuba Gragas [S|L] - 50% off
Miss FortuneSquare Secret Agent Miss Fortune [S|L] - 50% off
[13]
December 17
2015
December 17
2015
KarmaSquare Sun Goddess Karma [S|L] - 50% off
LuxSquare Imperial Lux [S|L] - 50% off
AkaliSquare Stinger Akali [S|L] - 50% off
ShenSquare Frozen Shen [S|L] - 50% off
KennenSquare Swamp Master Kennen [S|L] - 50% off
[14]
December 18
2015
December 18
2015
AlistarSquare Matador Alistar [S|L] - 50% off
ZileanSquare Time Machine Zilean [S|L] - 50% off
TeemoSquare Badger Teemo [S|L] - 50% off
MalphiteSquare Coral Reef Malphite [S|L] - 50% off
CaitlynSquare Sheriff Caitlyn [S|L] - 50% off
GragasSquare Vandal Gragas [S|L] - 50% off
[15]
December 18
2015
December 21
2015
KarthusSquare Statue of Karthus [S|L] - 50% off
XerathSquare Runeborn Xerath [S|L] - 50% off
TeemoSquare Cottontail Teemo [S|L] - 50% off
VeigarSquare Superb Villain Veigar [S|L] - 50% off
[16]
December 19
2015
December 19
2015
CorkiSquare Red Baron Corki [S|L] - 50% off
Miss FortuneSquare Road Warrior Miss Fortune [S|L] - 50% off
IreliaSquare Infiltrator Irelia [S|L] - 50% off
VladimirSquare Vandal Vladimir [S|L] - 50% off
AkaliSquare Crimson Akali [S|L] - 50% off
TristanaSquare Guerilla Tristana [S|L] - 50% off
[17]
December 20
2015
December 20
2015
MalphiteSquare Obsidian Malphite [S|L] - 50% off
EzrealSquare Nottingham Ezreal [S|L] - 50% off
SivirSquare Spectacular Sivir [S|L] - 50% off
MordekaiserSquare Dragon Knight Mordekaiser [S|L] - 50% off
AmumuSquare Almost-Prom King Amumu [S|L] - 50% off
AmumuSquare Pharaoh Amumu [S|L] - 50% off
[18]
December 21
2015
December 21
2015
TryndamereSquare Highland Tryndamere [S|L] - 50% off
BrandSquare Vandal Brand [S|L] - 50% off
PoppySquare Blacksmith Poppy [S|L] - 50% off
AsheSquare Freljord Ashe [S|L] - 50% off
MorganaSquare Sinful Succulence Morgana [S|L] - 50% off
Xin ZhaoSquare Winged Hussar Xin Zhao [S|L] - 50% off
[19]
December 22
2015
December 22
2015
AnnieSquare Annie in Wonderland [S|L] - 50% off
ShacoSquare Workshop Shaco [S|L] - 50% off
TryndamereSquare Viking Tryndamere [S|L] - 50% off
CorkiSquare Hot Rod Corki [S|L] - 50% off
TwitchSquare Kingpin Twitch [S|L] - 50% off
Dr. MundoSquare Executioner Mundo [S|L] - 50% off
[20]
December 22
2015
December 25
2015
HeimerdingerSquare Blast Zone Heimerdinger [S|L] - 50% off
VayneSquare Heartseeker Vayne [S|L] - 50% off
Dr. MundoSquare Rageborn Mundo [S|L] - 50% off
Miss FortuneSquare Arcade Miss Fortune [S|L] - 50% off
[21]
December 23
2015
December 23
2015
MorganaSquare Exiled Morgana [S|L] - 50% off
Kog'MawSquare Caterpillar Kog'Maw [S|L] - 50% off
AsheSquare Queen Ashe [S|L] - 50% off
RenektonSquare Galactic Renekton [S|L] - 50% off
VayneSquare Vindicator Vayne [S|L] - 50% off
Cho'GathSquare Nightmare Cho'Gath [S|L] - 50% off
[22]
December 24
2015
December 24
2015
OlafSquare Glacial Olaf [S|L] - 50% off
SonaSquare Muse Sona [S|L] - 50% off
VladimirSquare Count Vladimir [S|L] - 50% off
FiddlesticksSquare Fiddle Me [S|L] - 50% off
NocturneSquare Void Nocturne [S|L] - 50% off
GangplankSquare Sailor Gangplank [S|L] - 50% off
[23]
December 25
2015
December 25
2015
RenektonSquare Rune Wars Renekton [S|L] - 50% off
LeonaSquare Defender Leona [S|L] - 50% off
RumbleSquare Bilgerat Rumble [S|L] - 50% off
PoppySquare Noxus Poppy [S|L] - 50% off
HeimerdingerSquare Alien Invader Heimerdinger [S|L] - 50% off
RyzeSquare Professor Ryze [S|L] - 50% off
[24]
December 25
2015
December 28
2015
RenektonSquare Outback Renekton [S|L] - 50% off
VolibearSquare Captain Volibear [S|L] - 50% off
JayceSquare Debonair Jayce [S|L] - 50% off
Lee SinSquare Dragon Fist Lee Sin [S|L] - 50% off
[25]
December 26
2015
December 26
2015
Twisted FateSquare The Magnificent Twisted Fate [S|L] - 50% off
KennenSquare Deadly Kennen [S|L] - 50% off
GravesSquare Jailbreak Graves [S|L] - 50% off
EzrealSquare Explorer Ezreal [S|L] - 50% off
PantheonSquare Ruthless Pantheon [S|L] - 50% off
AlistarSquare Longhorn Alistar [S|L] - 50% off
[26]
December 27
2015
December 27
2015
KarthusSquare Phantom Karthus [S|L] - 50% off
SingedSquare Mad Scientist Singed [S|L] - 50% off
AnnieSquare Red Riding Annie [S|L] - 50% off
CaitlynSquare Safari Caitlyn [S|L] - 50% off
KassadinSquare Deep One Kassadin [S|L] - 50% off
NunuSquare Sasquatch Nunu [S|L] - 50% off
[27]
December 28
2015
December 28
2015
UdyrSquare Primal Udyr [S|L] - 50% off
JaxSquare Vandal Jax [S|L] - 50% off
KayleSquare Unmasked Kayle [S|L] - 50% off
ShenSquare Yellow Jacket Shen [S|L] - 50% off
Dr. MundoSquare Toxic Dr. Mundo [S|L] - 50% off
JaxSquare Angler Jax [S|L] - 50% off
[28]
December 29
2015
December 29
2015
ZiggsSquare Major Ziggs [S|L] - 50% off
SionSquare Hextech Sion [S|L] - 50% off
PantheonSquare Perseus Pantheon [S|L] - 50% off
WarwickSquare Feral Warwick [S|L] - 50% off
MalzaharSquare Vizier Malzahar [S|L] - 50% off
EvelynnSquare Masquerade Evelynn [S|L] - 50% off
[29]
December 29
2015
January 1
2016
Master YiSquare Samurai Yi [S|L] - 50% off
EvelynnSquare Safecracker Evelynn [S|L] - 50% off
KatarinaSquare Sandstorm Katarina [S|L] - 50% off
BlitzcrankSquare iBlitzcrank [S|L] - 50% off
[30]
December 30
2015
December 30
2015
Kog'MawSquare Sonoran Kog'Maw [S|L] - 50% off
MalphiteSquare Marble Malphite [S|L] - 50% off
MalphiteSquare Shamrock Malphite [S|L] - 50% off
AnnieSquare Prom Queen Annie [S|L] - 50% off
GalioSquare Hextech Galio [S|L] - 50% off
UrgotSquare Butcher Urgot [S|L] - 50% off
[31]
December 31
2015
December 31
2015
TwitchSquare Vandal Twitch [S|L] - 50% off
JannaSquare Tempest Janna [S|L] - 50% off
RyzeSquare Tribal Ryze [S|L] - 50% off
GarenSquare Desert Trooper Garen [S|L] - 50% off
SejuaniSquare Sabretusk Sejuani [S|L] - 50% off
VeigarSquare Baron Von Veigar [S|L] - 50% off
[32]
January 1
2016
January 1
2016
WarwickSquare Big Bad Warwick [S|L] - 50% off
TaricSquare Emerald Taric [S|L] - 50% off
RammusSquare Molten Rammus [S|L] - 50% off
NidaleeSquare Leopard Nidalee [S|L] - 50% off
Xin ZhaoSquare Viscero Xin Zhao [S|L] - 50% off
Dr. MundoSquare Mr. Mundoverse [S|L] - 50% off
[33]
January 1
2016
January 4
2016
RyzeSquare Uncle Ryze [S|L] - 50% off
AhriSquare Midnight Ahri [S|L] - 50% off
SingedSquare Augmented Singed [S|L] - 50% off
CassiopeiaSquare Jade Fang Cassiopeia [S|L] - 50% off
[34]
January 5
2016
January 8
2016
GalioSquare Commando Galio [S|L] - 50% off
RammusSquare Full Metal Rammus [S|L] - 50% off
VarusSquare Arclight Varus [S|L] - 50% off
Jarvan IVSquare Warring Kingdoms Jarvan IV [S|L] - 50% off
[35]
January 8
2016
January 1
2016
NocturneSquare Ravager Nocturne [S|L] - 50% off
Twisted FateSquare Red Card Twisted Fate [S|L] - 50% off
TryndamereSquare Sultan Tryndamere [S|L] - 50% off
LeonaSquare Iron Solari Leona [S|L] - 50% off
[36]
January 12
2016
January 15
2016
SivirSquare Warrior Princess Sivir [S|L] - 50% off
BrandSquare Apocalyptic Brand [S|L] - 50% off
AatroxSquare Justicar Aatrox [S|L] - 50% off
SwainSquare Tyrant Swain [S|L] - 50% off
[37]
January 15
2016
January 18
2016
LeBlancSquare Prestigious LeBlanc [S|L] - 50% off
ShyvanaSquare Ironscale Shyvana [S|L] - 50% off
NamiSquare Koi Nami [S|L] - 50% off
DariusSquare Bioforge Darius [S|L] - 50% off
[38]

References

LoL's Official Sales page