William John Paul Gallagher (born 21 September 1972) is an English singer and songwriter who is the lead singer and co-founder of the rock band Oasis. Gallagher fronted Beady Eye, an offshoot of Oasis, between 2009 and 2014, before starting a successful solo career in 2017. One of the most recognisable figures in British rock music, he is noted for his distinctive vocal style and outspoken personality.

Gallagher was interested in joining a band called the Rain. After mutual agreement, the band underwent a name change to Oasis, and his older brother Noel was initially approached to be their manager. Noel was subsequently extended an invitation to join the band as their lead guitarist and songwriter, which he accepted. The band's debut album, Definitely Maybe (1994), was a critical and commercial success amidst the emergence of Britpop. Their second album, (What's the Story) Morning Glory? (1995), reached the top of the album charts in many countries, and their third studio album, Be Here Now (1997), became the fastest-selling album in UK chart history. Britpop eventually declined in popularity, and Oasis failed to revive it; however, all of their subsequent albums topped the UK charts, and they continued to tour, playing gigs to 1,000,000+ people worldwide, but particularly in Europe, and South America. In August 2009, following Noel's departure from Oasis, Gallagher and the remaining band members would go on to form Beady Eye, with whom he released two studio albums before they disbanded in 2014.

In 2017, Gallagher began his solo career with the release of his debut solo album, As You Were (2017), which proved to be a critical and commercial success. It topped the UK Albums Chart and was the ninth fastest-selling debut album of the 2010s in the UK, with over 103,000 units sold in its first week. In 2018, the album was certified platinum with over 300,000 units sold in the UK. His second album, Why Me? Why Not, received mostly positive reviews and topped the UK charts upon its release in September 2019. This made it his tenth chart-topping album including eight with Oasis, and it also became the fastest-selling vinyl of 2019. In March 2010, he was voted the greatest frontman of all time in a reader poll by Q magazine. In 2019, he received the MTV Europe Music Award for "Rock Icon". Gallagher's third album, C'mon You Know, was released in 2022 and became his fourth solo album to debut at number one on the UK Albums Chart. In 2024, Gallagher collaborated with ex-Stone Roses musician John Squire on the studio album Liam Gallagher & John Squire, which was released on 1 March 2024.

Oasis's time was marked by turbulence, especially during the peak of Britpop, during which Gallagher was involved in several disputes with Noel. Their conflicts and wild lifestyles regularly made tabloid headlines. The band had a rivalry with fellow Britpop band Blur.

Gallagher was born in the Longsight area of Manchester on 21 September 1972, to Irish immigrant parents Peggy and Thomas "Tommy" Gallagher from Charlestown, County Mayo and Duleek, County Meath, respectively. As the youngest of three children, he has two elder brothers, Paul and Noel. Shortly after his birth, the family moved to Ashburn Avenue and then Cranwell Drive in the Manchester suburb of Burnage. As the eldest child, Paul was given his own bedroom while Liam had to share his bedroom with Noel.

When he was 10, Peggy took him and his brothers and left abusive Tommy, whom she divorced four years later. Although Liam maintained sporadic contact with his father throughout his teens, their issues remain unresolved. While drinking at a pub after an Oasis show in Ireland during the height of their fame, Liam noticed his father from across the room and had to be calmed down by Noel. A leaked phone call later revealed that he subsequently called his father and threatened to break his legs if he ever saw him again.

Gallagher was educated at St. Bernard's RC Primary School and the Barlow Roman Catholic High School in Didsbury. Despite common reports that he was expelled at age 16 for fighting, he was actually suspended for three months. He then returned to school, where he completed his last term and gained four GCSEs in 1990. He preferred sports at a young age, having no interest in music. During his teens, he suffered a blow to the head with a hammer from a student at a rival school, which he credits with changing his attitude towards music. After this incident, he became infatuated with the idea of joining a band. He became confident in his ability to sing and began listening to bands like the Beatles, the Stone Roses, the La's, the Who, the Kinks, the Jam, and T. Rex. In the process, he became obsessed with the Beatles' John Lennon, and would later sarcastically claim to be Lennon reincarnated despite being born eight years prior to Lennon's death. Liam and Noel attended a Stone Roses benefit gig at International 2 in 1988; both brothers claim that if they had not gone to that gig, Oasis would never have happened. Liam later claimed: "That was my favourite gig of all time, killed me dead, changed me fuckin' life. If I hadn't gone that night, I'd probably be sitting in some pub in Levenshulme." He would also help Noel with his job as a roadie for Inspiral Carpets and worked as a tax collector for HM Revenue and Customs.

"Liam? We wouldn't have been what we were without him, that's for sure. As important and as vital as those songs were and still are, I think the two elements that made Oasis was his thing and them songs. If it wasn't for him we might have been just another band. I couldn't imagine anybody else being the singer."