Rafael Nadal is the most-followed active tennis player on Instagram however there are quite a few players that hung it up with a lot of social media followers.
Instagram isn't a really good metric for much of anything but it's an interesting way to compare the 'popularity of players'. The more followers you the more popular you seem to be. Right now, Nadal is the most followed tennis player on the platform which should surprise no one. He is probably the most popular active tennis player right now,
He leads a list of players that includes Djokovic at number two, Kyrgios at number 3, Osaka at 4 and Raducanu at 5. There are quite a few players that are not active anymore but have a lot of followers. Mainly we have Serena who has 16.3 million which is still 1.6 million shy of Nadal's 17.9 Would be good enough for number two ahead of Djokovic though.
Other players are Federer with 11.3 million which would place 3rd behind Djokovic. Then Sania Mirza who would be 4th Sharapova who would be 5th.