What spirits can be lethal?

Answer 1

most spirits can be lethal like Dark Entities (Note: Fallen Angels would apply here but don't think for one moment that all fallen angel's are bad, Some of them are fallen angels because they were wrongfully accused of something or took the blame for someone else, Not all of them are bad, But be careful with them in case you happen upon one that is trouble)

or others such as, Poltiergiest / Poltergeist Shadows

Orbs these types of ghost can kill you most times and at times there are ghosts that will stick to you if released from the spirit world (aka realm of the dead or Shadow world) these types of ghost are lethal and are usually called Dark Entities like demons, and things like that.