These are a list of aliases presumed by various characters in The Office.
Dwight Schrute
Mr. Poop
"Mr. Poop" is an alias of Dwight Schrute used by Jake Palmer in the episode "Take your daughter to work day" to torment him. Dwight finds both this and the fact that he calls his mother by her name, "Meredith" disrespectful.
Dragon
"Dragon" is an alias used for Dwight Schrute by him and Ryan Howard in order to keep their plans to demote Jim Halpert secret. It is used in the episode, "Manager and Salesman."
Bobcat
"Bobcat" is an alias used for Ryan Howard by Dwight Schrute in order to keep their plan to demote Jim Halpert secret. It is used with Dwight's aforementioned alias, "Dragon."
Angela Martin
Monkey
"Monkey" is an alias for Angela used by her and Dwight Schrute in order to keep their relationship secret. It is used many times throughout the series. When their relationship was made public, Dwight continued to call Angela monkey in an affectionate manner.