Monster-X is the mysterious Horror from HorrorLand, who has been contacting Lizzy Morris and Luke Morris very secretly. He is mentioned on the blog on EscapeHorrorLand.com and in the Welcome To Horrorland Survival Guide. He is also the Horror who gave them the blank card which was originally for Britney Crosby, but it ended up to the siblings. Monster-X is not Byron, but actually Ned who is also a horror in Horrorland. This is told in The Streets Of Panic Park.