Kairoz

Love the name of this NPC as its a reference to an ancient greek belief.

The ancient Greeks had two words for time, chronos and kairos. While the former refers to chronological or sequential time, the latter signifies a time between, a moment of indeterminate time in which something special happens. What the special something is depends on who is using the word. While chronos is quantitative, kairos has a qualitative nature.

It fits quite nicely with the island in which this NPC shows up, as the regular time (Chronos) is permanently frozen, while the qualitative time (kairos) is in constant motion, and great special events will take place in it, including the pet tournament, the celestial trials, the etching of the legendary cloak and so much more.

All, in the island were time stands still.

Spoiler

During Blizzcon today, Tom Chilton accidentally let it slip that Kairoz is the one who helps Garrosh go back in time to Draenor.

Update as of April 25, following an early release of the novel War Crimes:

Spoiler

While Kairoz does free Garrosh, it's actually all a part of Wrathion's plan. Kairoz is working with him.

This member of the Bronze dragonflight, found at the Celestial Court on the Timeless Isle, is part of a quest chain that takes place here and he also offers quests to venture into the new raid- the Siege of Orgrimmar.

Lead-up quests before you encounter him:
A Flash of Bronze...
Journey to the Timeless Isle
Time Keeper Kairoz

Quests he offers as part of the chain:
A Timeless Tour/Time In Your Hands
The Essence of Time
He then offers optional side quests, one leading to Emperor Shaohao, and the others relating to events/killing rares (also elite).
Empowering the Hourglass (weekly version)

He will then begin the Siege of Orgrimmar section of the chain, requiring extensive use of the [item=105935] :
A Vision in Time
Refining the Vision
Seeking Fate
Hidden Threads
Courting Destiny
One Final Turn