Durnan of the Yawning Portal

Durnan (pronounced: /ˈdʌrˈnɑːn/ Durr-NAN), occasionally known as Durham, was the gruff tavernkeeper who ran the Yawning Portal Inn and considered himself the self-appointed gatekeeper to Undermountain. He was known for having explored Undermountain.
Relationships
Durnan was friends with Khelben "Blackstaff" Arunsun. He had a secret association with the Red Sashes, a group that committed vigilantism.
He was married to Mhaere Dryndilstann and had a daughter with her called Tamsil Dryndilstann whom she taught the basics of battle to give her the necessary skills against problematic customers.
He also had a special relationship with the local clergy of Tymora. He daily paid the deity's temple to send one of their clerics over to heal people. This service was not charity on the temple's side. It was not merely expected but paying donations to the caster was actually enforced and Lady Luck's clerics accepted nothing but cash, meaning no credits.
As an additional security, Durnan hired skilled fighters, who were at all times armed, to pretend being customers. These people were no mere mercenaries but were incredibly loyal to Durnan. So loyal in fact that magically compelling them to disobey or harm Durnan, his family, or the family's property was not just impossible but actually something that broke the spell.
History
Durnan was born in the remote North in 1283 DR. He started adventuring with Mirt when the two were ten.
In the Year of the Broken Helm, 1302 DR, Durnan and Mirt the Merciless went into Undermountain and managed to come back not only alive but also rich. This was one of the first instances of somebody surviving a foray into Halaster's property. He used the looted wealth to tear down the remnants of Halaster's Hold to build the Yawning Portal inn. He spread the information about the size and the wealth that could be found in Undermountain. Combined with the good location, on which he built his inn, it guaranteed him his living by selling equipment to people who wanted to enter the dungeon too. Durnan retired as an adventurer. The reason for this was that he made a promise to his girlfriend at that time to come back to her when he managed to become rich.
Durnan has recently been freed from months of captivity spent at the hands of Xanathar and the Lord of Blades.  A select group of adventurers has taken it upon themselves to ensure his safety and the continued function of the Yawning Portal with him as the sole proprietor.