Whateley Academy Wiki
Maggie Finson provided the basis for this article in Questions and Answers: Power Categories.

Esper (ESP)[]

"ESP are all alternate perception (extra sensory perception): anything that lets you 'sense' something that isn't sight with your eyes, sound with your ears, scent with your nose, taste with your tongue, or feel pressure/temperature with your 'skin'... is ESP. From a practical standpoint all 'psychic' abilities form from ESP of some sort. In order to read or project emotions, you typically have to be able to sense them. In order to communicate telepathically, you first have to have the ability to 'sense' the energy patterns of thought. In order to be able to manipulate machines or interact with code within computers, you first have to be able to read the energy patterns that make up the operation of those things.[1]
So, on the surface level, all psychic abilities are variants or extensions of some form of ESP. From there, you have to determine 'where' the sense occurs... is it within the self? within the aura/mental sheath? or outside of the boundaries that define the person? And do you have the ability to alter what you sense?"[1]

It's a far more useful and powerful category than most people realize, as it gives the esper information that can be crucial, at the moment that it's most needed.

Levels and supplemental info is somewhat special for the esper type. Since the many esper talents vary greatly, there are different ranking scales for each such talent.

For many talents, level defines how reliable and controllable the senses are, NOT how powerful the trait is. For these traits, a common leveling scale used is:

Level 1 Flashes arrive at unpredictable times, duration unpredictable, vision cannot be controlled.
Level 2 Mutant can trigger the sense deliberately, duration somewhat controllable, sometimes vision can be steered or targeted.
Level 3 All aspects of the sense are completely controllable.

The three level scale measures controllability, it does not measure power. Esper talents that are common enough, such as Gadgeteers, to quantify ability or power levels frequently have their own individual scale.

Supplemental info is not assigned to letters: it is far too varied for that. More than anything else, it is these details rather than the level that describe how interesting and 'powerful' an esper is. A level 1 precog is far more interesting than a level 3 (range 0) clairvoyant.

Other talents include:

Astral projector (The astral body can fly swiftly to see and hear things very far away. If the mutant can see/affect dreams or the minds of living people, it may be a telepathic skill.)
Aura reader Some people would like to make this a sub-category of telepathy
Clairvoyant Vision, but also applied to other "tele-senses"
Danger sense A form of precognition. You KNOW that you're in danger, in time to take some action to mitigate it if you react instantly.
Detective A focused version of the Paragon trait specialising in investigation.[2]
Diviner Differs from a Precog in that a diviner asks specific, focused questions.
Dowser A finder that uses a physical focus to find (usually) natural resources.
'Empathy ' Some argue that this is a sub-category of telepathy. There are both projector (pro) and receiver (rec) variants. It's rated on the 1 to 7 scale.
"Finder" Many categories: object types, people, etc.
Gadgeteer See specific writeup.
New senses e.g. see gravity waves, smell zones of good & bad luck, hear the voice of trees.
Paragon A paragon instinctively knows what to do, and how to do it.
Precog At some level, the ability to foretell the future, or possible futures.
Psychometrist A "post-cog," most commonly triggered by touching an object.
Reincarnator May overlap with "avatar." The esper version is usually limited to vision-flashes of the past life.
Super senses Telescopic/microscopic vision.