Immortals can apply to several things:

- They can be people with very long lifespans

- They can be people who never age

- They can be people who only die under certain circumstances

- They can be people who never die

Many different species and peoples fall under this category, but not all of them are Higher Beings like we are. Some of them do become Higher Beings. Most of them merely live long lives or can survive all but a few things. It depends on who you asks for what the definition is, however this is the general list.