It is difficult to determine the most famous painting in the world, as opinions on art are subjective and can vary greatly from person to person. However, some paintings that are widely recognized and considered to be among the most famous in the world include:

1. The Mona Lisa, a portrait painted by Leonardo da Vinci in the early 16th century. It is one of the most famous paintings in the world, and is housed at the Louvre museum in Paris, France.
2. The Starry Night, a landscape painting by Vincent van Gogh. It is known for its vivid colors and swirling brushstrokes, and is housed at the Museum of Modern Art in New York City.
3. The Persistence of Memory, a surrealist painting by Salvador Dali. It is known for its melting clocks and dreamlike imagery, and is housed at the Museo Nacional Centro de Arte Reina Sofía in Madrid, Spain.
4. The Scream, an expressionist painting by Edward Munch. It is known for its depiction of a person screaming in agony or terror, and is housed at the Munch Museum in Oslo, Norway.
5. The Last Supper, a painting by Leonardo da Vinci that depicts the last meal shared by Jesus and his disciples before his crucifixion. It is housed at the Santa Maria delle Grazie monastery in Milan, Italy.

These are just a few examples of famous paintings, and there are many other works of art that are also highly regarded and widely known.