One of Masson's most famous works is his use of the technique of automatism, which is a method of creating art through spontaneous, subconscious action. He applied this technique to his paintings, drawings, and collages, and his work often featured disturbing and dreamlike imagery.
One of his most famous works is "Battle of Fishes" (1926) which is a painting that depicts a chaotic, violent scene of fish fighting against each other. The painting is considered an expression of the violence and chaos in the world. Another famous work is "The Cyclops" (1944) which is a painting that depicts a one-eyed giant, the painting is an exploration of the human psyche and the subconscious mind.