lastguardian
nounUK /ˌlɑːstˈɡɑːdiən/
US /ˌlæstˈɡɑːrdiən/
The last person who keeps something safe.
The lastguardian of the old library locked the doors every night.
OTHER MEANINGS
2. The final remaining person responsible for watching over a place or thing.
As the lastguardian of the lighthouse, she kept the light burning through the storm.
3. A hero in a story who is the only one left to defend a kingdom or treasure.
In the tale, the lastguardian stood alone at the gate against the invading army.
4. The last line of defense or protection for something valuable.
The old firewall was the lastguardian between the virus and the files.