I posted about Betelgeuse reaching 140% of its normal brightness a few days ago[0], but to my knowledge this is the brightest we've ever recorded it. As I mentioned in that older post, scientists believe Betelgeuse (which is about 642.5 light years away from Earth) could go supernova at any point within the next 100,000 years.
[0]https://news.ycombinator.com/item?id=35692234