Microsoft co-founder and billionaire philanthropist Bill Gates is set to guest star on CBS sitcom The Big Bang Theory during season 11. The 62-year-old tech titan is of course one of the world?s richest men, with an estimated net worth of over $80 billion. He?d actually be much richer at this point, were it not for Gates opting to frequently donate large portions of his vast wealth to charitable causes, and operate his own charities alongside wife Melinda. Gates remained on-board as chairman of Microsoft until stepping down from that post in 2014.