According to the search results, there are several serial killers who have killed a significant number of people. However, the most prolific serial killer in US history is Samuel Little, who confessed to killing 93 people between 1970 and 2005. It is worth noting that the exact number of victims assigned to a serial killer is not always known, and even if that person is convicted of a few, there can be the possibility that they killed many more. Therefore, it is possible that there are other serial killers who have killed more people than Samuel Little, but their crimes have not been discovered or confirmed.