Negavance
To advance one's own agenda, career, reputation, etc. at the expense of another person or group, specifically by criticizing, tearing down, embarrassing, or belittling that person or group. Such behavior is in lieu of advancing one's own agenda, career, reputation, etc. solely on the merits of such.
We've all seen people in the office who like to negavance into job promotions or sweet assignments -- they usually leave a trail of bodies.
negavator
The opposite of a motivator, someone who puts you down or just has negative energy
Justin: Why won’t he stop being so annoying?
Justin’s friend: Just ignore him, he’s a negavator.
Justin’s friend: Just ignore him, he’s a negavator.
negaventful
A circumstance where every event that happens is negative or terrible in some way
"My dog died this morning, I got fired from my job and my wife is sleeping with the neighbor. I'm just having a very negaventful day."