At the beginning of each new year, YouTube takes a moment to celebrate the top ads of the previous year, with the annual YT Ads leaderboard. The list is determined using some of YouTube's strongest signals of viewer choice – including factors like watch time, views, and mix of paid/organic views. Today, we announce which brands and agencies appear on the year-end YouTube Ads Leaderboard. “Congratulations to each of the brands, creative agencies, and media agencies on this list for embracing the storytelling power of YouTube,” said Ilias Sousis, Head of Domestic Greek Business, Agencies and YouTube. In 2017, as in every other year, clarity of purpose, generosity of spirit and finesse in execution mark out top performers.