Throughout the history of horror movies, there have been many actors who were inherently associated with the genre like Boris Koloff, Vincent Price, Robert Englund, Christopher Lee, and Dee Wallace. However, A-list Hollywood actors generally tend to avoid acting in horror movies.
Whether it's because they are better known for award-winning dramatic or comedic roles or because they think horror is low-brow entertainment, there are some who simply wouldn't act in a horror movie no matter who is directing or how good the script is.
However, that doesn't mean that all famous movie stars have nothing to do with the horror genre at all. Since they tend to have a lot of money, many successful actors form production companies, and some of them do not limit their projects to just movies that they appear in. Sometimes these outside projects include horror movies, which make attractive investments because most are made quickly and cheaply.
Scary movies therefore have the potential to make incredible profits at the box office and in home media sales. So while it's not likely they'll actually appear in too many horrors, some famous faces are more than happy to bank some of those profits...