The March Hare, often called the Mad March Hare, is a character from the tea party scene in Lewis Carroll's Alice's Adventures in Wonderland. The main character Alice hypothesises,

"The March Hare will be much the most interesting, and perhaps as this is May it won't be raving mad -- at least not so mad as it was in March."

"Mad as a March hare" was a common phrase in Carroll's time, and appears in John Heywood's collection of proverbs published in 1546. It is reported in The Annotated Alice by Martin Gardner that this is based more on popular belief than science. The saying refers to the hare's behaviour at the beginning of the long breeding season, which lasts from February to September, when unreceptive females use their forelegs to repel overenthusiastic males.