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The Prime Minister of New Zealand features alongside actor Dwayne "The Rock" Johnson, singer Khalid, Game of Thrones actress Emilia Clarke and Hilary Clinton.
Ardern's blurb is written by London Mayor Sadiq Kahn, who writes how Londoners were "heartbroken to wake up to news of the horrific terror attack in Christchurch, shocked by the callous targeting of innocent civilians for no reason other than their faith".
Kahn states that Ardern's leadership since then "has been an inspiration to us all".
"Not only is she delivering such swift action on gun control, she has sent a powerful message around the world about our shared values - that those who seek to divide us will never succeed, and that New Zealand will always protect and celebrate the diversity and openness that make our countries so great."
The Time list features the world's most influential pioneers, leaders, titans, artists and icons and also includes US president Donald Trump and environmentalist Jane Goodall.
Kahn went on to state that Londoners stood "shoulder to shoulder with the people of Christchurch".
"We will never forget that when terror sent ripples of fear through communities around the world, New Zealand's Prime Minister proudly stood up for hope, unity and inclusiveness in the face of fear, division and hatred."
US Democratic Party member Alexandria Ocasio-Cortez also makes the list. Her rapid rise to both renown and notoriety is also described; how she went from working behind a bar 12 months ago to now being admired and followed by millions.
Michelle Obama, Taylor Swift, Lebron James, Lady Gaga and Rami Malek are also on the list.