From lowest to highest:

None: Self explanatory, literally no stamina at all. Sentient objects are included in this category.(Example: Sealed Bella Noche from Adventure time)

Very low: Characters and beings that can barely do any effort or almost never move. They usually have some sort of disability, illness or restrictions. (example: Stephen Hawking) 

Low: Characters and beings that can tire out fairly easily even from the most basic of actions. (example: babies)

Below average: Characters and beings that have slightly lower stamina than the average human (example: Shiro from No game No life)

Average: Characters and beings with average human stamina. (example: half the human beings in real life)

Above average: Athletic human stamina. characters and beings that can't tire out easily by the usage of their respective verse's techniques and spells and competitive athletes. (example: Real life professional athletes)

High: Characters and beings that have the capacity to fight for prolonged periods of times without tiring out. Can also be used for characters that can use techniques and spells that are deemed high level in their verses. Put in simple words, superhuman stamina. (example: Boa Hancock from One Piece)

Very high: Characters and beings that dont get tired out despite the consecutive usage of high level techniques or beatings which would drastically exhaust even some superhumans. (example: Ryner Lute from The legend of legendary heroes)

Extremely high: Characters that can only tire out after days of heavy effort or after taking deadly beatings and even then they usually have the capacity to continue to fight. (example: The Soul of Cinder from Dark souls)

Nigh limitless: Characters and beings that can almost never be tired out. They sometimes have some sort of outside/inside power source backing their capacity to fight and keep fighting/traveling for weeks on end. Their power sources might need "recharging" on some accounts. (example: The Crystal Gems from Steven Universe)

Limitless: Self explanatory. Simply put beings who can perform any and all action without ever reaching a limit to their stamina (example: Magic gods from ToAru)