kitchen; galley; (Internet) troll
person who attends meetups or uses social media to proposition people for sex
would-be creator (esp. writer) who is overly preoccupied with the background setting of their story
nostalgic person; person who prefers the good old days; fuddy-duddy
person who posts unwanted advice in the comments section or chat of an online video or live stream (esp. Let's Play videos)
summerfag; young and inexperienced user who joins an online community during the summer
ragequitter; person who disconnects from an online game (when losing)
person who identifies someone's private information (esp. through online research); doxxer; doxer; person who identifies real-life locations or items appearing in anime, video games, etc.
person who argues that everything is better abroad (esp. football); self-hating Japanese