Kathy Brier, who was born on March 10, 1975 in Staten Island in New York, began acting in theater productions such as Funny Girl, I Oughta Be in Pictures, Cinderella and Grease. For off-Broadway, she appeared in Bat Boy The Musical, The Prince and the Pauper, O'Casey Knock and Tango Ballad. In 2002, Brier was cast for the role of Macie McBain on the soap opera One Life to Live, her first major television role. For this portrayal she received a nomination for Daytime Emmy Award's Outstanding Supporting Actress in a Drama Series category.

Marcie Walsh McBain is played by Kathy Brier on One Life to Live. Marcie came to Llanview to attend college and while at Llanview University, she became a receptionist at the Llanview Hospital. There, she met Jennifer Rappaport, a university student who later became her best friend and Al Holden, who was also studying at the university. Later, she discovered Al's drug addiction, which she helped him get over. The two developed a relationship shortly thereafter. Al was then diagnosed with a terminal disease which soon took his life. A devastated Marcie met Michael McBain and fell in love with him. The two got married and adopted a boy named Tommy, as Marcie couldn't bear children.