The biggest name one so far is the H3H3 trial.[1] One that looks to be settled soon is Akilah Hughes suing Carl Benjamin (Sargon of Akkad), where all that Benjamin does is edit together two of Hughes videos with the only original addition being a new title. This is almost certainly going to go in favor of Sargon, yet YouTube's algorithms turned up to the nth degree would almost certainly have blocked it.[2]
If you go outside of YouTube, fair use law in the United States is very broad. Just look at what Richard Prince does with others' art. [3]
edit: added links
1. http://www.bbc.co.uk/newsbeat/article/41037631/youtube-stars...
2. https://www.youtube.com/watch?v=6LMgGBDZbJY
3. https://www.theguardian.com/technology/2015/jul/18/instagram...