The Winter season in MMORPGs is a time playful celebration, gift-giving, and snow-driven quests. The City of Heroes Winter Event is usually celebrated from the middle of December through the beginning of January and blanket-covers most of the real world’s winter holidays. City of Heroes characters receive buffs just for signing in – each player is gifted with the Holiday Spirit and Holiday Cheer Temporary Powers, which grant 48 hours of 25% Debt Protection and the ability to grant someone else a Temporary Power or gift of winter clothing respectively.
World of Warcraft’s winter shenanigans are called The Feast of the Winter Veil (also known as the Feast of the Great-Winter) and also lasts several weeks. Along with wintery decorations throughout the villages, seasonal fare shops are also open in the major cities and holiday goodies like candy canes, Winter Ale and mistletoe can all be purchased. 
Winter missions are also a fun part of this snowy holiday. Those playing City of Heroes can complete the Father Time Mission, which rescues the kidnapped Baby New Year so that time can move forward and keep the world from ending. Not a mission but a game, characters can also try their snow boots out on a trip or two down the snowy ski course and ski run. Talented participants can earn themselves badges for their performance.
WoW offers players a couple of holiday quests as well, including the Alliance (or Horde) Crest Metzen the Reindeer (levels 60 and above). Another hidden surprise is the Winter Wondervolt Machine (located near the entrance of several cities) which transforms your character briefly into a Winter Veil gnome.
Beyond these basic holiday celebrations, there are many others offered throughout the year in several different MMORPGs, each with their own flavor and lore.
World of Warcraft holidays and festivals include:
The Lunar Festival
Brewfest
Children’s Week
Love is in the Air
Midsummer Fire Festival
New Year
Noblegarden
Pirate’s Day
Dance of the Earth Mother
Feast of Scribes
Peon Day
Renewal of the Sun
Kosh’harg Celebration
Warhammer Online Holidays (Imperial)
New Years Day – Witching Day
Spring Equinox – More-Growth
Summer Solstice – Sun Still
Day of Mystery – Mystery Day
Autumn Equinox – Less-Growth
Winter Solstice – World-Still
Also keep an eye out for:
The Starlight Festival – the Winter festival for Final Fantasy XI
The Celestial Nights Festival – the Summer festival for Final Fantasy XI that requires players to write real-world poetry. Yes, poetry!