changing table ownership

I need to change permissions on some tables in our database. When the database was set up tables were added by several users, and so they have different owners, one of whom is no longer at the company. I would like to change the ownership of all tables to one user, because I can not guarantee that any of the staff will be here forever and because permissions can not be changed except by the original owner. How can I change the owners without dumping out the entire database? Thanks in advance.