Hierarchy of Alienness

Although the Ender’s Game series had a Hierarchy of Foreignness, SF still seems to have a lot of human-like aliens. So I’m suggesting a different hierarchy:

• Human
  • Looks human, speaks an Earth language
• Humorous Humanesque
  • look human for budgetary reasons
  • appearance in-universe is explained by handwaving
  • e.g., Ford Prefect from Hitchhiker’s Guide, Doctor Who
• You Wouldn’t Understand Our True Form
  • look human most of the time
  • appearance in-universe is that they change form for our convenience
  • more powerful (or expensive visual effects) than you can possibly imagine
  • e.g., Q from Star Trek, aliens from Contact (the movie), Thermians from Galaxy Quest
• Prosthetic Foreheads on Their Real Heads
  • humanoid
  • appearance is based on budget
  • good for a thinly veiled metaphor
  • appearance in-universe is explained as a ‘progenitor species’ / common origin
  • Universal translator easily translates their language into English/Galactic standard
  • e.g. Vulcan, Klingon, individual Borg
• ‘We’re Really Alien’ Aliens!
  • non-humanoid but otherwise easy to communicate with
  • higher budget and/or CGI
  • e.g., Star Trek Discovery’s Tardigrade, Horta
• Abstract Idea
  • not photogenic
  • sentient form of something inanimate
  • communication with humans is complicated
  • e.g., Hooloovoo from Hitchhiker’s Guide, aliens from Contact (book), entire planet from Rick & Morty episode ‘Childrick of Mort’, Borg collective, heptapods from Arrival