After a historic vote, Vladimir Putin could remain in power in Russia until 2036. Here are 15 of the world's longest-serving leaders.

Yoweri Museveni, Paul Biya, and Vladimir Putin.James Akena/Charles Platiau/Reuters/Sergei Savostyanov/Getty Images

• In a national referendum, Russians overwhelming voted in favor of constitutional amendments that would allow Putin to extend his administration through to 2036, giving him the potential to become one of the world's longest-serving leaders.
• Yoweri Museveni has been the president of Uganda since 1986.
• Ayatollah Ali Khamenei, Iran's supreme leader, has been in power since 1989.

Although many countries have fixed terms for how long a leader can stay in power, other nations, like Iran, Cameroon, and Uganda, have leaders who have ruled for decades.

This week, Vladimir Putin was declared victorious in a Russian vote on a referendum that would allow him to potentially remain in power for another 16 years, bringing his total time in office to 32 years.

In Iran and Uganda, Ayatollah Ali Khamenei and Yoweri Museveni, respectively, have been leading their countries since the '80s, and have ruled in five consecutive decades.

Take a look at the world's longest-serving leaders.