"Lonely Day" is a song by Armenian-American heavy metal band System of a Down. It was released in 2006 as the second single from their fifth album Hypnotize (2005), and written by guitarist Daron Malakian, who also provides lead vocals on this track. The song received a nomination for Best Hard Rock Performance at the 49th Annual Grammy Awards.^[3]

The song is featured in the 2007 film Disturbia, as well as the film's trailer; however, it is not included in the film's soundtrack. The song was also featured in an episode of the 2023 Netflix series Beef.

The music video opens with a shot of downtown Los Angeles, with the traffic light at the corner of S Broadway & 6th St on fire. The video continues with shots of the band members. There are other various shots of other items that are on fire. In order of appearance, they are as follows: a padlock, a building, shrubs in front of an office building, a newspaper dispenser, a shopping cart, a pay phone, a train car, a stack of wooden pallets, several trees, a billboard, a single car in traffic among other non-burning cars, an advertisement in Chinese at a bus stop, a bench at a train station, a dumpster, a building, and the roof of a gas station.

• Daron Malakian – guitars, lead vocals
• Serj Tankian – keyboards, backing vocals
• Shavo Odadjian – bass
• John Dolmayan – drums