Ad Reinhardt was an American abstract painter. He was active from the 1930s through the 1960s and is most famous for his "Black Paintings". He was a part of the abstract expressionist movement during WWII along with famous artists like Jackson Pollock.
What I find most interesting about Reinhardt's works in "The Black Paintings" is that, while at first they seem to be simple square canvases painted black, there is so much more to se up close. He created these pieces with intention and many people might think it is not art. However, the purpose and reasoning behind these pieces are the art in and of itself.
While these paintings both appear black, at another place you can see that they actually contain shapes and other colors. Reinhardt's intention is essentially to create nothing by using something. He chose his canvas size in order to create the illusion of having so size. They are 5 ft high and 5 ft wide, the height of a person and the width of a person's outstretched arms. They use different shades of black, vertical and horizontal lines, and painting techniques to create a size-less, lightless, colorless, and composition-less piece of artwork, which I find fascinating.
This resource shows the art pieces and gallery labels of "The Black Paintings" by Reinhardt.
This article goes into more detail about Reinhardt's life, art, and inspiration as well as some insight into his works.
This is a biography on Ad Reinhardt, which includes explanation of some of his other great art works.