Barbara Ann Mikulski (born July 20, 1936) is an American politician of the Democratic Party, and the Senior Senator from the state of Maryland. She is Maryland's first female senator. She is currently the most senior female Senator, having served since 1987, and ranking 18th (out of 100) in seniority. She received 1,504,691 votes in her 2004 reelection campaign, the largest number of votes to date for a Senate candidate in Maryland.

The great-granddaughter of Polish immigrants who owned a local bakery, Barbara is the oldest of three daughters of Christine Kutz and William Mikulski. She was born and raised in historic and ethnically diverse East Baltimore. During her high school years at the Institute of Notre Dame, she worked in her parents' grocery store, delivering groceries to seniors in her neighborhood who were unable to leave their homes.

After graduating from Mount Saint Agnes College (now a part of the Loyola College in Maryland), she obtained her masters degree in social work (MSW) from the University of Maryland School of Social Work. She worked as a social worker for Catholic charities and Baltimore's Department of Social Services, helping at-risk children and educating seniors about the Medicare program. Mikulski became an activist social worker when she heard about plans to build a 16-lane highway through Baltimore's Fells Point and Canton neighborhoods. She helped organize communities on both sides of the city and stopped the construction of the road, saving Fells Point and Baltimore's Inner Harbor.