What important/crucial real-world applications use blockchain?

Question

As part of some blockchain-related research I am currently undertaking, the notion of using blockchains for a variety of real-world applications are thrown about loosely.

Therefore, I propose the following questions:

1. What important/crucial real-world applications use blockchain?
2. To add on to the first question, more specifically, what real-world applications actually need blockchain - who may or may not currently use it?

From a comment, I further note that this disregards the notion of cryptocurrencies. However, the use of smart contracts can have other potential applications aside from benefits they can pose to the area of cryptocurrencies