Barbara Ann Mikulski (born July 20, 1936) is the senior United States Senator from Maryland and a member of the Democratic Party. Mikulski, the first woman elected to the Senate from Maryland, is the longest-serving female senator and the second longest-serving female member in the history of the United States Congress (only after Edith Nourse Rogers). If she stays in office until March 17, 2022, she will become the longest-serving female member in the history of the United States Congress.

Mikulski is chairwoman of the Health Subcommittee on Primary Health and Aging and Appropriations Subcommittee on Commerce, Justice, Science, and Related Agencies, and is a member of the Select Committee on Intelligence. Mikulski is the longest serving present Senator who has never been the chairperson of a full standing committee, and Mikulski is the longest serving/highest ranking Democrat who is not a present chairperson of a full standing committee of the U.S. Senate.

The great-granddaughter of Polish immigrants who owned a local bakery, Barbara Mikulski is the oldest of three daughters of Christine Eleanor (née Kutz) and William Mikulski. She was born and raised in the Highlandtown neighborhood of 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.