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
Early Sales


Period Sales Link
November 21
2014
November 24
2014
SingedSquare Augmented Singed [S|L] - 50% off
LuxSquare Spellthief Lux [S|L] - 50% off
GravesSquare Hired Gun Graves [S|L] - 50% off
[1]
November 25
2014
November 28
2014
VayneSquare Dragonslayer Vayne [S|L] - 50% off
SejuaniSquare Bear Cavalry Sejuani [S|L] - 50% off
RammusSquare Freljord Rammus [S|L] - 50% off
[2]
November 28
2014
December 1
2014
Xin ZhaoSquare Winged Hussar Xin Zhao [S|L] - 50% off
PantheonSquare Perseus Pantheon [S|L] - 50% off
ShyvanaSquare Boneclaw Shyvana [S|L] - 50% off
[3]
December 2
2014
December 5
2014
TryndamereSquare Sultan Tryndamere [S|L] - 50% off
SyndraSquare Justicar Syndra [S|L] - 50% off
WarwickSquare Big Bad Warwick [S|L] - 50% off
[4]
December 5
2014
December 8
2014
EliseSquare Death Blossom Elise [S|L] - 50% off
GarenSquare Rugged Garen [S|L] - 50% off
TrundleSquare Lil' Slugger Trundle [S|L] - 50% off
[5]
December 9
2014
December 12
2014
AnnieSquare Reverse Annie [S|L] - 50% off
Jarvan IVSquare Warring Kingdoms Jarvan IV [S|L] - 50% off
NasusSquare Pharaoh Nasus [S|L] - 50% off
[6]
December 12
2014
December 15
2014
ZyraSquare Wildfire Zyra [S|L] - 50% off
WukongSquare General Wukong [S|L] - 50% off
Master YiSquare Chosen Master Yi [S|L] - 50% off
[7]
December 16
2014
December 19
2014
RengarSquare Headhunter Rengar [S|L] - 50% off
PantheonSquare Full Metal Pantheon [S|L] - 50% off
ShacoSquare Royal Shaco [S|L] - 50% off
[8]
December 19
2014
December 22
2014
RenektonSquare Bloodfury Renekton [S|L] - 50% off
MorganaSquare Blade Mistress Morgana [S|L] - 50% off
OriannaSquare Gothic Orianna [S|L] - 50% off
[9]
December 23
2014
December 26
2014
Lee SinSquare Dragon Fist Lee Sin [S|L] - 50% off
NautilusSquare AstroNautilus [S|L] - 50% off
NidaleeSquare Pharaoh Nidalee [S|L] - 50% off
[10]
December 26
2014
December 29
2014
AhriSquare Popstar Ahri [S|L] - 50% off
LeonaSquare Defender Leona [S|L] - 50% off
ZileanSquare Groovy Zilean [S|L] - 50% off
[11]
December 30
2014
January 2
2015
GangplankSquare Sultan Gangplank [S|L] - 50% off
SorakaSquare Celestine Soraka [S|L] - 50% off
IreliaSquare Aviator Irelia [S|L] - 50% off
[12]
January 2
2015
January 5
2015
OlafSquare Pentakill Olaf [S|L] - 50% off
KarmaSquare Sun Goddess Karma [S|L] - 50% off
LuxSquare Commando Lux [S|L] - 50% off
[13]
January 6
2015
January 9
2015
KatarinaSquare Bilgewater Katarina [S|L] - 50% off
ViktorSquare Creator Viktor [S|L] - 50% off
Twisted FateSquare Jack of Hearts Twisted Fate [S|L] - 50% off
[14]
January 9
2015
January 12
2015
YorickSquare Pentakill Yorick [S|L] - 50% off
TaricSquare Armor of the Fifth Age Taric [S|L] - 50% off
GalioSquare Commando Galio [S|L] - 50% off
[15]
January 13
2015
January 16
2015
ShenSquare Warlord Shen [S|L] - 50% off
YasuoSquare High Noon Yasuo [S|L] - 50% off
UdyrSquare Black Belt Udyr [S|L] - 50% off
[16]
January 16
2015
January 19
2015
NamiSquare Koi Nami [S|L] - 50% off
VolibearSquare Northern Storm Volibear [S|L] - 50% off
Xin ZhaoSquare Imperial Xin Zhao [S|L] - 50% off
[17]
January 20
2015
January 23
2015
DravenSquare Gladiator Draven [S|L] - 50% off
GarenSquare Steel Legion Garen [S|L] - 50% off
VayneSquare Aristocrat Vayne [S|L] - 50% off
[18]

References

LoL's Official Sales page