Thailand's king is Bhumibol Adulyadej, 86, and it's hard to overstate his importance in Thailand. He's the world's longest-serving monarch, and perhaps the most revered. His portrait hangs on government buildings, in taxicabs, in living rooms. Politicians often seem in a competition to claim their love for him. It's sort of creepy, at times. Stiff lese majeste laws prevent Thais from speaking about the king in any way that's critical.
The king has long been a behind-the-scenes mediator in Thailand's disputes, but this time around, he appears too ill to play that role. Instead, it's the question about his succession that is driving instability. It's not yet clear who will succeed the king — it could be his far-less-beloved son — but either way, when King Bhumibol passes away, Thailand's constitutional monarchy will be shaken to the core. And Thailand will have at least a partial power vacuum.