What is the title of a person who rents a room to someone?

Renter.

Landlord, Owner, Room Mate, One who Rents out, good question.

I would think the renter is landlord, rentee is tenant.

If you own a house and rent a room out to someone else, you are the landlord, the landlady, the deedholder, the owner, the property owner, the proprietor, the rentier (not the renter), and the lessor. At the same time, if you also live in the house you are a room-mate or a house-mate.

The person who is renting the room from you is the tenant, the lessee, the renter, the occupant, the resident, the lodger, the boarder, the paying guest, or the leaseholder, as well as being a room-mate or a house-mate.

I call mine Davis.
technically I think landlord is the right term.

I can’t remember exactly, but I do know Medieval Rules require you offer your wedding night to them first.

Well you can rent a house, apartment and sublet a portion of it. But subletter is not usually a title. I suppose the renter would consider that person a landlord, but the person who owns deed to the property is the official landlord.

It would behoove anyone interested in this arrangement to consider who exactly is the landlord and if in fact the person subletting the room has permission to do so. If the landlord did not agree to it, the second renter may be evicted and maybe even the subletter who rented him the room…and that would suck.

Landlord in residence?

That would be subletting if someone were renting a property they themselves are renting.
If they own the property and rent out a room they are a landlord.

The person who collect the rent is the rentor (landlord) and the person who pays the rent is the renter.

Edit: they are both housemates or roommates.

You are called the Tenant; the person subleasing from you is the Subtenant.

Sublessee.