Brenda Mersereau Helser (May 26, 1924 – March 26, 2001), later known by her married name Brenda Helser de Morelos, was an American former competition swimmer who won a gold medal in the women's 4×100-meter freestyle relay at the 1948 Summer Olympics in London. A graduate of Stanford University, de Morelos grew up in Oregon where she graduated from Lincoln High School. Her swim coach was International Swimming Hall of Fame member Jack Cody. Along with fellow 1948 Olympians Suzanne Zimmerman and Nancy Merki, Helser was part of the Multnomah Athletic Club team dubbed "Cody's Kids" that from 1939 to 1948, won 58 individual national swimming titles and three national team swimming championships.