Monica Hughes appeared originally in Saints Row 2 and is the Mayor of Stilwater. She is vengeful against the Ultor Corporation for stealing her husband's work and developing the Saint's Row District. She appears in a "Septic Avenger" activity where she along with the Protagonist spray raw sewage over Ultor owned properties.
Monica returns in the sequel Saints Row: The Third in a more prominent role. When her husband's memorial bridge is destroyed during a conflict between the 3rd Street Saints and Killbane's Luchadores, she deploys a military group named STAG to Steelport to deal with the gang activity. During the course of the game she gets infuriated with STAG leader Cyrus Temple's lack of results, although she refuses him to declare martial law in order to deal with the Saints. Sick of Cyrus' failings, she heads to Steelport herself.
In the canon "Save Shaundi" ending, the Saints save a bridge that STAG attempted to destroy to set them up. Monica changes her mind (in order to keep on the public's side) and declares the Saints heroes, whilst also disgracing Cyrus.
In the non-canon ending "Kill Killbane", if Cyrus succeeded in destroying the bridge she gives him permission to declare martial law. However the Saints stop their plans and the Protagonist kills Cyrus, and then declares Steelport and independent city state.
In the Saints Row: The Third DLC Genkibowl VII, a news ticker in the opening cutscene reveals Monica has put in for a presidential bid. However in Saints Row IV she loses out to the Saints when the Protagonist becomes President of the United States. Monica later went on to start writing her autobiography. Her fate during Zinyak's invasion of earth and eventual destruction is unknown.