On January 5, Lincoln Chafee filed with the Federal Election Commission as a Libertarian presidential candidate. The filing says his campaign manager is Christopher Thrasher. See the filing here. Thanks to Jim Riley for the link.
Chafee has been elected Governor of Rhode Island, and also U.S. Senator from Rhode Island. He was elected Governor in 2010 as an independent. He is age 66. When he was a Republican U.S. Senator in 2003, he was the only Republican Senator to vote against going to war against Iraq. Here is a Rhode Island news story about his filing.