Who is the youtube that has most subscribers?
No context provided
Who became the YouTube channel with the most subscribers on Dec 23, 2013?
PewDiePie
No context provided
Who became the YouTube channel with the most subscribers on Dec 12, 2013?
YouTube Spotlight
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Who became the YouTube channel with the most subscribers on Dec 8, 2013?
PewDiePie
List of most-subscribed YouTube Music artists
https://en.wikipedia.org/wiki/List%20of%20most-subscribed%20YouTube%20Music%20artists
List of most-subscribed YouTube channels
https://en.wikipedia.org/wiki/List%20of%20most-subscribed%20YouTube%20channels
Kjellberg's channel became the most-subscribed on YouTube on 15 August 2013, but after he publicly vied for the title with T-Series in 2019, it currently holds the title of the fourth-most subscribed, albeit remaining the most-subscribed operated by an individual. 
PewDiePie
Felix Arvid Ulf Kjellberg (/ˈʃɛlbɜːrɡ/ SHEL-burg, Swedish: [ˈfěːlɪks ˈǎrːvɪd ɵlf ˈɕɛ̂lːbærj] (About this soundlisten);[c] born 24 October 1989), better known online as PewDiePie (/ˈpjuːdiːpaɪ/ PEW-dee-py), is a Swedish YouTuber known primarily for his Let's Play videos and comedic formatted shows.
PewDiePie
On 22 December 2013, his channel overtook the YouTube Spotlight channel to once again become the most-subscribed on YouTube.
PewDiePie
YouTube (formerly YouTube Spotlight) is YouTube's official YouTube channel for spotlighting videos and events on the platform.
YouTube (channel)
Felix Arvid Ulf Kjellberg's YouTube channel, PewDiePie, had the most subscriptions as of Dec 8, 2013. However, YouTube's own channel, YouTube Spotlight, surpassed his on Dec 12, 2013. This didn't last long, though. PewDiePie, once again, ranked number one on Dec 22, 2013. Currently, the PewDiePie channel sits in fourth place.