The mystery of Jack the Ripper's identity is still a mystery, although many, many men have been named as suspects at one time or another. One of the more far-fetched was Lewis Carroll, who published Alice's Adventures in Wonderland in 1865. The Ripper murders took place more than twenty years later, beginning in 1888. The connection between Carroll and the Ripper wasn't made until 1996, when author Richard Wallace wrote about the possibility.
Of the names discussed, few would be more surprising than Carroll's. Born in 1832, he was sent to a boarding school at the age of 12 and sometimes wrote home expressing despondence over the nighttime racket. In Wallace’s book, Jack the Ripper: Light-Hearted Friend, he seizes this declaration to be a hint that Carroll was being physically abused by the older boys at the school, suffering a psychotic break that would plague him for the rest of his life.
Wallace’s theory requires a large and ambitious leap to a conclusion: that Carroll, famously fond of wordplay and anagrams, kept sneaking hidden messages into his correspondences and his published works that provided insight into his state of mind.
It appears to be a pretty thin theory, but you can read about Wallace's ideas and see some of Carroll's possibly ambiguous messages in an article at Mental Floss.