John Michael "Ozzy" Osbourne (ওজি অসবোর্ন) was an English singer, songwriter and media personality. He rose to prominence during the 1970s as the lead vocalist of the heavy metal band Black Sabbath, during which period he adopted the nickname "Prince of Darkness".

John Michael Osbourne was born at the maternity hospital in Marston Green (then in Warwickshire) on 3 December 1948, and grew up in the Aston area of Birmingham. His mother, Lilian (née Unitt; 1916–2001), was a non-observant Catholic who worked at a Lucas factory. His father, John Thomas "Jack" Osbourne (1915–1977), worked night shifts as a toolmaker at the General Electric Company. Osbourne had three older sisters named Jean, Iris, and Gillian, and two younger brothers named Paul and Tony. The family lived in a small two-bedroom home at 14 Lodge Road in Aston. Osbourne gained the nickname "Ozzy" as a child. He dealt with dyslexia at school. His accent was described as "hesitant Brummie".

At the age of 11, he suffered sexual abuse from school bullies. He said he attempted suicide multiple times as a teenager. He participated in school plays, including Gilbert and Sullivan's The Mikado and H.M.S. Pinafore. Upon hearing the first hit single of the Beatles at age 14, he became a fan of the band and credited their 1963 song "She Loves You" with inspiring him to become a musician. In the 2011 documentary God Bless Ozzy Osbourne, Osbourne said that the Beatles made him realise that " was going to be a rock star the rest of life".

Osbourne had over 15 tattoos, the most famous of which were the letters O-Z-Z-Y across the knuckles of his left hand. This was his first tattoo, created by himself as a teenager with a sewing needle and pencil lead. A longtime fan of the comedy troupe Monty Python, in a 2010 interview with Us Weekly Osbourne stated, "My favourite movie is Monty Python's Life of Brian". Osbourne suffered minor burns after a small house fire in January 2013. On his 65th birthday on 3 December 2013, he asked fans to celebrate his birthday by donating to the Royal Marsden cancer charity in London.

Though Osbourne had long been accused of being a Satanist, The New York Times reported in 1992 that he was a practising member of the Church of England and prayed before each show. In 2002, Osbourne and wife Sharon were invited to the White House Correspondents' Association dinner by Fox News Channel correspondent Greta Van Susteren for that year's event. President George W. Bush noted Osbourne's presence by joking, "The thing about Ozzy is, he's made a lot of big hit recordings – 'Party with the Animals', 'Sabbath Bloody Sabbath', 'Facing Hell', 'Black Skies' and 'Bloodbath in Paradise'. Ozzy, Mom loves your stuff."

Osbourne had six children; three from his first marriage and three from his marriage to Sharon Osbourne.

In 1971, Osbourne met his first wife Thelma Riley at the Rum Runner, the Birmingham nightclub where she worked. They were married later that year and children Jessica and Louis were soon born. Osbourne also adopted Riley's five-year-old son Elliot from a previous relationship. Osbourne later referred to his first marriage as "a terrible mistake". His use of alcohol and other drugs, coupled with his frequent absences while touring with Black Sabbath, took their toll on his family life; his children later complained that he was not a good father. In the 2011 documentary film God Bless Ozzy Osbourne, produced by his son Jack, Osbourne admitted that he could not even remember when Louis and Jessica were born.

Osbourne used tobacco, alcohol, street drugs, and prescription drugs for most of his adult life. He admitted to Sounds in 1978, "I get high, I get fucked up ... what the hell's wrong with getting fucked up? There must be something wrong with the system if so many people have to get fucked up ... I never take dope or anything before I go on stage. I'll smoke a joint or whatever afterwards." Black Sabbath bandmate Tony Iommi said that while all the band were involved with alcohol and other drugs to various degrees in the 1970s, Osbourne had the unhealthiest lifestyle of them all. Despite this, said Iommi, he was typically the only one left standing when the others were "out for the count". Longtime guitarist Zakk Wylde has attributed Osbourne's longevity in spite of decades of substance misuse to "a very special kind of fortitude that's bigger than King Kong and Godzilla combined... seriously, he's hard as nails, man!" In 2010, during an interview on The Howard Stern Show, Ozzy said that it took him 19 attempts to get his driving licence because of his alcohol use.