Wikipedia says:

In Internet terminology, a troll is a person who enters an established community such as an online discussion forum and intentionally tries to cause disruption, most often in the form of posting inflammatory, off-topic, or otherwise inappropriate messages

What is a troll in Chinese? I don’t think there is a term. Wikipedia’s “in other languages” sidebar offers up 小白 for troll, but that just means idiot or annoyer, someone with a thick skin or someone who doesn’t get it; so no, that’s not exactly a troll. It doesn’t capture the aspect of intention and the not infrequent subtlety of trolling. The article on 小白 itself is hilarious. It’s obvious the usage is restricted to Taiwan.

Mainland and overseas Chinese BBS are full of subtlety to begin with, for reasons not worth mentioning at this moment. Maybe every Chinese is a native troll. Certain Chinese history points to training in – ah nevermind, I’m trolling. However, a subset of more benign trolling behavior seems to elicit more condemnation on these Chinese BBS and have terms associated with them. For instance: posting off-topic messages and inappropriate messages can take the form of 刷屏 or repeated re-posting, or posting in multiple sub-forums. Posting a stream of emoticons or other useless messages (to readers) such as 顶, 批, 阅, 路过 to increase the number of posts by one is known as 灌水. The meaning of 灌水 has expanded to include, in some cases, posts that are not just useless, but specifically useless for ongoing rational discussion. Since a post that elicits 灌水 behavior is known as a 坑 and somebody who writes such is engaging in 挖坑, then 挖坑 may yet emerge as the logical equivalent of trolling (verb). It has been used in that sense already.

Still no word for troll (noun), though 坑王 is a good candidate.