From the passage note down the various celebrities who joined TikTok . List the results in comma separated format.

Context: ByteDance planned on Douyin expanding overseas. The founder of ByteDance, Zhang Yiming, stated that "China is home to only one-fifth of Internet users globally. If we don't expand on a global scale, we are bound to lose to peers eyeing the four-fifths. So, going global is a must."

The app was launched as TikTok in the international market in September 2017. On 23 January 2018, the TikTok app ranked first among free application downloads on app stores in Thailand and other countries.

TikTok has been downloaded more than 130 million times in the United States and has reached 2 billion downloads worldwide, according to data from mobile research firm Sensor Tower.

In the United States, celebrities, including Jimmy Fallon and Tony Hawk, began using the app in 2018. Other celebrities, including Jennifer Lopez, Jessica Alba, Will Smith, and Justin Bieber joined TikTok as well as many others.

In January 2019, TikTok allowed creators to embed merchandise sale links into their videos.

On 3 September 2019, TikTok and the U.S. National Football League announced a multi-year partnership. The agreement occurred just two days before the NFL's 100th season kick-off at Soldier Field, where TikTok hosted activities for fans in honor of the deal. The partnership entails the launch of an official NFL TikTok account, which is to bring about new marketing opportunities such as sponsored videos and hashtag challenges. In July 2020, TikTok, excluding Douyin, reported close to 800 million monthly active users worldwide after less than four years of existence.

Answer: Jimmy Fallon, Tony Hawk, Jennifer Lopez, Jessica Alba, Will Smith, Justin Bieber