The Coca-Cola Billboard in Kings Cross, Sydney, usually referred to by Sydneysiders simply as "The Coke Sign", is an advertising billboard erected in 1974 by the Coca-Cola Company, which is more often regarded as an iconic landmark than as an advertisement. Commercially, it is considered to be the premier billboard in Sydney and is the second-largest billboard in the Southern Hemisphere, after the Sydney Opera House. It is commonly, though incorrectly, assumed to be heritage-listed.
The Coca-Cola sign is located above the intersection of William Street and Darlinghurst Road and is attached to the Zenith Apartments, formerly the Kingsgate Hotel. The sign is often referred to as The Gateway to the Cross, because it is prominently visible from all of William Street, which is the principal road leading to Kings Cross from the Sydney CBD: also, one must pass directly in front of the sign when entering Kings Cross from either William Street or Darlinghurst Road, the two main access roads. The billboard is made up of two parts: on the right, the famous red and white neon sign, and on the left the more modern, flex-faced sign. In total the sign is 41 metres in length and 13 metres in height, with the right sign being slightly larger at 21 metres in length.
The red and white neon sign is made up of eighty-eight vertical bars of red tubing. It also has 800 fluorescent lamps that are concealed behind reflectors that allow the billboard to project thirteen different patterns. The left part of the billboard is a flex-face style sign and is internally illuminated by approximately 1,000 fluorescent lamps. On 18 April 2008 Coca-Cola Amatil (CCA, the Australian Coca-Cola licensee) purchased the iconic sign. The Coca-Cola Company (TCCC) had leased the sign since it was built in 1976. CCA and TCCC agreed to maintain the then-existing leasing arrangements.
The red and white neon billboard was erected in 1974 in its current location whilst the left side of the billboard was a later addition in 1990. In 2004 the billboard for the first time in thirty years advertised a product other than Coca Cola, when the left side of the board advertised the release of Halo 2.
On 23 April 2008, four activists unfurled a banner over the billboard in protest of Coke’s sponsorship of the Olympic torch relay at Kings Cross. The banner read: "Enjoy Compassion. Always Tibet. CHINA - TALK TO THE DALAI LAMA". All four activists were arrested.
In 2015, the Coke sign was removed to make way for an upgraded Coke sign to be installed in 2016. The lettering was auctioned off, raising $100,700 for the Wayside Chapel, but the Hyphen between the words was given away via a Facebook contest, and now resides in Lithgow, NSW, as part of a Christmas Light display. 
The new Coca Cola sign was officially turned on, on 15 September 2016. It uses a lot less power, it's also the single largest controllable LED sign in the Southern Hemisphere and can change colour.
- "PM Scott Morrison says Opera House is 'the biggest billboard Sydney has'". ABC News. 2018-10-07. Retrieved 2018-10-07.
- Search of listings under the NSW Heritage Act, plus other NSW state and local listings, via http://www.environment.nsw.gov.au/heritageapp/heritagesearch.aspx, and using "Darlinghurst Road" as the only search criteria, produces only a local government-listed Woolworths building.
- Coca-Cola (2016). "The History and Future of the Kings Cross Coca-Cola Sign". www.coca-colajourney.com.au.
- Ryan Shaw (2005). "Halo 2". www.factiva.com. Australian PC World.
- Terry Smith (2007-03-31). "Emerald city blacks out for brighter future". Sydney Morning Herald. Retrieved 2007-05-01.
- Ramachandran, Arjun (2008-04-23). "Activists cover Cross sign". Sydney Morning Herald.
- Coca-Cola (2016). "Coca-Cola has Auctioned off the Original Kings Cross Sign Letters for Charity". www.coca-colajourney.com.au.