Big O

• Big Omega function (disambiguation), various arithmetic functions in number theory
• Big O notation, asymptotic behavior in mathematics and computing
• Time complexity in computer science, whose functions are commonly expressed in big O notation

• Omar Gooding (born 1976), American actor, rapper, voice artist and comedian
• Oliver Miller (1970–2025), American professional basketball player
• Takashi Nagasaki (born 1958), Japanese author
• Barack Obama (born 1961), 44th President of the United States
• Roy Orbison (1936–1988), American singer-songwriter
• Glenn Ordway (born 1951), Boston-area sports radio host
• Otis Redding (1941–1967), American soul singer-songwriter and record producer
• Oscar Robertson (born 1938), former professional basketball player
• Oscar Santana, American radio personality
• Oprah Winfrey (born 1954), American television host, producer and philanthropist
• Oscar McInerney (born 1994), Australian rules footballer

• Big O (Ferris wheel), the world's largest centerless Ferris wheel, in Japan
• Big "O", a structure on Skinner Butte in Eugene, Oregon, United States, listed on the National Register of Historic Places
• Olympic Stadium (Montreal), Quebec, Canada; the main venue of the 1976 Summer Olympics
• Ontario Motor Speedway, California, USA; former superspeedway racecar track

• The Big O, a 1999 Japanese animated TV series
• Omega (Ω), a Greek letter, whose name translates literally as "great O"
• Big O Tires, a tire retailer in the United States and Canada
• The Big O (album), by Roy Orbison
• Big Orange Chorus, a barbershop men's chorus in Jacksonville, Florida

• Bigo (disambiguation)

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