Worst: Tiger Woods
In golf and gratuity circles -- which surprisingly don't intersect much -- Tiger Woods is known as a notoriously shitty tipper, often leaving his dining/gambling cohorts (who are almost always not as rich as Woods) with the onus of leaving a tip. But Tiger may have an excuse: the dude apparently doesn't carry cash. I guess top-tier escorts take AmEx now?
Best: Bill Murray
In my (kind of) esteemed, professional opinion, William James Murray is the 21st century's archduke of badassery. Not only will he sometimes jump behind a bar and give everyone tequila shots, he also generously compensates service workers. There have been myriad stories about Murray's tipping prowess, but one in particular, in which Murray drops a 120% tip on a bill, then teaches the same server how to make their lemon wedges juicier by rolling them on a cutting board before slicing them, shows his benevolence.