A cat co-authored a scientific paper in 1975, when his owner, a physicist named Jack H. Hetherington, decided to add him as a second author to avoid changing the plural pronouns in his manuscript. The cat’s name was Chester, and he was given the pen name F.D.C. Willard, which stood for Felix Domesticus, Chester. Willard was also the name of Chester’s father. The paper was about atomic behavior at different temperatures, and it was published in Physical Review Letters, a prestigious physics journal. Chester’s co-authorship was revealed when Hetherington sent some signed copies of the paper to his friends and colleagues, and included the cat’s paw prints as his signature. The story became widely known and amused many people in the scientific community. Chester even published another paper as the sole author in 1980, in a French popular science magazine. He died in 1982, but he is still remembered as the first and only cat to have authored a published scientific paper.