Stefani Joanne Angelina Germanotta (born March 28, 1986), known professionally as Lady Gaga, is an American singer, songwriter, and actress. She is known for her self-empowering messages, fashion, and live performances. Gaga initially performed in theater, appearing in high school plays, and studied at CAP21 through New York University's Tisch School of the Arts before dropping out to pursue a musical career. After leaving a rock band, participating in the Lower East Side's avant garde performance art circuit, and being dropped from a contract with Def Jam Recordings, Gaga worked as a songwriter for Sony/ATV Music Publishing. There, recording artist Akon noticed her vocal abilities and helped her to sign a joint deal with Interscope Records and his own KonLive Distribution.

Her debut album The Fame (2008) was a critical and commercial success that produced global chart-topping singles such as "Just Dance" and "Poker Face". A follow-up EP, The Fame Monster (2009), was met with a similar reception and released the successful singles "Bad Romance", "Telephone", and "Alejandro".

Her second full-length album Born This Way was released in 2011, topping the charts in more than 20 countries, including the United States, where it sold over one million copies in its first week. The album produced the number-one single "Born This Way".

Her third album Artpop, released in 2013, topped the US charts and included the successful single "Applause". In 2014, Gaga released a collaborative jazz album with Tony Bennett titled Cheek to Cheek, which became her third consecutive number one in the United States.

For her work in the television series American Horror Story: Hotel, Gaga won a Golden Globe Award in 2016. With global album and single sales of 27 million and 146 million respectively, as of January 2016, she is one of the best-selling musicians of all time.

Her achievements include 12 Guinness World Records, six Grammy Awards, and a Songwriters Hall of Fame's Contemporary Icon Award—first artist ever to win. Other accolades includes a Fashion Icon lifetime achievement award from the Council of Fashion Designers of America (2011), regular appearances on Billboard's Artists of the Year lists and Forbes's power and earnings rankings.

In 2013, Gaga finished second on Time's readers' poll about the most influential people of the past ten years, while in 2015, she was named Billboard's Woman of the Year. She is noted for her philanthropic endeavors and social activism, including LGBT rights, HIV/AIDS prevention and the Born This Way Foundation.