The most viral video ever is a subjective question and can vary depending on the criteria used to measure viral success. However, as of 2021, the most viewed video on YouTube is "Baby Shark Dance" by Pinkfong, with over 12 billion views. Another highly successful viral video is "Despacito" by Luis Fonsi ft Daddy Yankee, with over 7 billion views. PSY's Gangnam Style was the first to surpass the billion-view mark in 2012.