Neal delivers. I recently learned that viruses are not considered living being, but I'm nevertheless happy they're included here because they're both relevant and interesting in this context.
Not that I'm qualified to reply, but I think this is debated. I seem to recall reading in "Immune" by Philipp Dettmer that there is an argument that a virus is analogous to a spore stage of life, and the virus begins "living" when it plants itself inside a cell full of "nutrients", sheds it's skin and begins consuming and replicating.
It is always going to be controversial but after discovery of prions - needle shifted to "self-replicating means nothing and viruses are also dead". Then scientists also found viruses large enough that they get infected with other viruses, and parasitic cells that are missing most parts required for metabolism, so it is getting more fuzzy again.