Bobby Smith contested David Cameron’s Witney seat at the General Election dressed in an Elmo suit where he secured 37 votes.
He represents New Fathers 4 Justice, a campaign group demanding better access rights for fathers to their children.
Last year he was one of two men who scaled the roof of a building at Buckingham Palace as part of their campaign.
By-elections have a long history of attracting fringe candidates looking for publicity for their causes.