Nothing is known about Dennis's life before the apocalypse, except the fact that he had a sister named Denise, who described him as being brave, yet dangerous; it is likely that because of this behavior, this is the reason he died during the early days of the apocalypse.
Dennis was, mentioned by Denise, brave but also angry, same as Daryl's brother, Merle, and that he was born "6 minutes" before his sister.
This list shows the victims Dennis has killed:
- Possibly numerous counts of survivors or unnamed people
- Numerous counts of zombies
His death was not explicitly mentioned by Denise, but it is known that he died during the apocalypse.