I Wayan Koster (Balinese: ᬇ​ᬯᬬᬦ᭄​ᬓᭀᬲ᭄ᬢᬾᬃ; born 20 October 1962) is an Indonesian politician and economist who is the 9th governor of Bali from 2018 to 2023.

Before becoming a politician, he was involved in education, Koster studied at Bandung Institute of Technology and Jakarta State University before becoming a lecturer and eventually joining Indonesian Democratic Party of Struggle.

[8][9] By 2003, Koster was a specialist staff member in PDI-P.[8] In 2004, he ran for a seat in the House of Representatives of the Republic of Indonesia as part of PDI-P. During the campaigning process, he headed a committee for a rally supporting the party in his hometown.

[12][17] During most of his time in parliament, Koster was part of the tenth commission covering education, culture, sports, tourism, and the creative economy.

[23] During the campaigning period, Koster stated that he wished to alter the family planning program in Bali by changing the recommended number of children from two to four in order to fit Balinese traditions.

[26] On August 23 2024 Koster again ran for Governor of Bali in the Bali gubernatorial election, He was again promoted by the Indonesian Democratic Party of Struggle (PDIP), this time He was accompanied by the Regent of Badung for two terms I Nyoman Giri Prasta who was considered more qualified and well-known among Balinese people than previous vice governor Cok Ace.

On January 9 2025 I Wayan Koster and I Nyoman Giri Prasta were officially appointed as Governor and Vice Governor of Bali elected by the General Elections Commission of Bali Province in an Open Plenary Meeting on January 9 2025 based on Bali Province General Election Commission Decision Number 26 of 2025 On February 15 2016, Koster asked to the Indonesian Film Producer Association (APROFI) whether there was any investment originating from China.

[30] On December 1, 2016, Koster stated his notes that the debate on the National Examination (UN) had been going on since 2004 and the DPR's position at that time was against the UN.

Wayan argued that the quality of education was not the same as the UN because psychologically the UN was used as prestige in several regions, thus opening up opportunities for leaks.

[31] On September 29, 2015, Koster opined that the current budget posture of the Ministry of Research, Technology and Higher Education (Kemristekdikti) is very vulnerable.

[33] On September 11, 2014, Wayan Koster said that the Jokowi and Jusuf Kalla government should not merge four ministries that carry out basic service functions.

"Institutional change with an efficiency approach alone cannot be based on theory on paper, but must be combined with previous government experience, so as not to be lulled by beautiful expressions that can actually lead you astray," said Koster at the DPR Building, Jakarta, Thursday (11/9/2014).

Wayan urged the Secretary General of the Ministry of Education and Culture (Sekjen Dikbud) to change the budget note.

[35] [36] On March 17, 2015, Koster stated that he believed the 4th Indonesian Democratic Party of Struggle (PDI-P) congress would be quiet.

The reason is, the majority of administrators, from the center to the regions, agreed to re-appoint Megawati Soekarnoputri as general chairperson again.

On 21 March 2023, Koster stated that he rejected the participation of the Israel national under-19 football team in the 2023 FIFA U-20 World Cup, then scheduled to be held in Bali.

[38] After FIFA announced that Indonesia was removed as a host of the U-20 World Cup, Indonesian internet users expressed their frustration by flooding Koster's Instagram account comment column.