Lourdes Aflague "Lou" Leon Guerrero (born November 8, 1950) is a Guamanian politician and former banking executive, lobbyist, and nurse who has served as the ninth governor of Guam since 2019. A member of the Democratic Party, Guerrero is the first woman to serve in the position. Leon Guerrero had served in the Guam Legislature from 1995 to 1999 and again from 2001 to 2007. From 2007 to 2017, Leon Guerrero was president and CEO of the Bank of Guam.

Born and raised in Guam, Leon Guerrero received her B.S. in Nursing from Cal State Los Angeles and a MPH from the University of California, Los Angeles. Leon Guerrero worked as a nurse in California and Guam, eventually becoming president of the Guam Nurses Association. In this role, she opposed efforts to outlaw abortion on the island. Leon Guerrero won election to the Guam legislature in 1994, serving two terms before unsuccessfully running for lieutenant governor in 1998. She went onto serve in the Guam legislature again from 2001 to 2007, before leaving public service to work in the private sector until 2017.

Leon Guerrero re-entered politics to mount a campaign for governor of Guam in the 2018 gubernatorial election. Leon Guerrero and her running mate Josh Tenorio defeated Republican opponent Ray Tenorio, and was inaugurated as governor on January 7, 2019. In office, Leon Guerrero has signed legislation to raise the minimum wage in Guam and coordinate the territory's response to the COVID-19 pandemic. As governor, Leon Guerrero has vetoed efforts by the Guam Legislature to institute further restrictions on abortion in Guam. She was reelected to a second term in the 2022 election.

Born in Guam, Lou Leon Guerrero is the daughter of Jesus Sablan Leon Guerrero (1927–2002), founder of the Bank of Guam, and Eugenia Calvo Aflague Leon Guerrero. She has two brothers, Jesse and Anthony (1952–2005). She attended the Academy of Our Lady of Guam High School, moving to the U.S. mainland to study and work in Southern California.

In 1973, Leon Guerrero earned her Bachelor of Science degree in Nursing at California State University, Los Angeles. She went on to attain a Master of Public Health degree at the University of California, Los Angeles (UCLA) in 1979. In 2009, she went back to school in Seattle, Washington to receive a master's degree from Pacific Coast Banking School.

Lou Leon Guerrero worked as a staff nurse at Santa Monica Hospital in Santa Monica, California, before returning to Guam in 1980. She worked at Guam Memorial Hospital in 1980, eventually becoming the hospital's assistant nursing director. She then went to work at the Family Health Plan clinic and served as Director of Operations (1990–1994).

In 1989, Leon Guerrero, as the president of the Guam Nurses Association, provided the sole testimony from a Chamoru woman against Bill 848, a legislative measure intended to outlaw abortion on the island.

Leon Guerrero served as a senator of the 23rd, 24th, 26th, 27th, and the 28th sessions of the Guam Legislature. Leon Guerrero authored the public law which created the Healthy Futures Fund, which currently funds medical care and cancer research in Guam. In addition, she introduced and secured the passage of the Natasha Protection Act, which regulates public smoking.