Birthday: March 10 Glen was the head of the Baskerville family 100 years ago. According to Lotti, Glen gave the impression that he liked being alone and was difficult to approach. Contrary to her beliefs, he was best friends with the loud Jack Vessalius and even told him about a secret passage so that he could sneak into the Baskerville house. Jack and Glen made a musical pocket watch together. Glen wrote the melody for it while Jack crafted it. The piece he wrote is called "Lacie".
One day he suddenly ordered his subordinates to kill everyone in the castle of Sabrié, the incident later known as the "Tragedy of Sabrié". He was killed by Jack but, according to Jack, Glen is still alive. He controls a chain called Jabberwock which looks like the jabberwocky from Through the Looking-Glass and four others being the Dodo, the Owl, the Griffon, and Raven.
It was then revealed in one of Alice's memories that Glen made the pocket watch in the memories of Lacie, a precious person to Glen. The pocket watch's melody was named after and used to be sung by Lacie. (Lacie is possibly an anagram of "Alice".) In chapter 37 Oz finally came face to face with Glen in Sablier's memory world, and is shocked when Glen knows him as well as Jack. Having lost Lacie, Glen appears to believe that the world is worthless and that not even hope or despair is left within him.
Chapter 39 also implies that Glen might never been a human but a "spirit" that is the Baskerville's head and must continue for eternity thus the necessity of having new bodies through the five chains with black feathers. Glen's next body was supposed to be Gilbert with Raven as the chosen chain.
His sister, Lacie, is revealed to be the mother of Alice Baskerville and The Intention of the Abyss, thus making them his nieces. While he took care of Alice he knew of the Intention's existence and rarely allowed them to leave the tower.