Predatory Talker
A person who lurks around corners and in break rooms at work with the soul purpose of trapping you into long, boring conversations. The talker will often stalk you, ask you a meaningless question, the answer to which they could care less about, and before you can even respond begin a one sided, often insanely idiotic monologue, thereby trapping you into a pointless conversation and wasting hours of precious life.

Note: The predatory talker is not technically a person, they are an asshole, and should be treated as such.
I walked out of the bathroom and there standing in the doorway was John, the office's predatory talker, I tried my best to give him a head nod and walk past, but what started as a question about how my weekend was turned into a 45 minute monologue about his high blood pressure.