Shane Johnson - the greatest unrecognized actor in the world of moviemaking - and no I won’t concede to anything else.
For me I follow:
** Al Pacino** He was good in the 70’s
** Bob De Niro** He was God in the 70’s
Angelina Jolie I want to have intimate moments with her
Sean Connery He’s Scottish
Director wise: anything by Scorcese
I missed out Clint Eastwood.
Every film he’s been in or directed is worth a watch.
**Barbara Harris ** I put in the Link because I guess no-one else would know who she was. Scroll down a bit for movie stills, the top of the page is Broadway(?) stuff.
I have watched (and bought) some pretty tacky movies because she was in them, though she’s often the best thing in an otherwise dull flick. I got the original cast recording of On a Clear Day You Can See Forever where she was the lead, and she can really sing! (they gave the lead in the film version to Barbara Streisand 
)
I can’t say I’ve been “following her career” since most of her good stuff was done quite a while before I was paying attention, but i’ll watch anything with her in it.
she is THAT great.
Yeah, I said “even if you don’t think they’re THAT great”, but I guess we can ignore that to just include anybody’s career you MUST follow for whatever reason.
In that case, I’ll mention Anthony Hopkins. He’s only been my favorite actor for a few years now, but I try and see any movie with him in it. This means seeing not-so-great recent movies like “Bad Company” and “The Grinch that Stole Christmas” (he was the narrator). It also means tracking down hard to find movies from the 1970s/early 1980s through eBay or the Inter-Library Loan like “All Creatures Great and Small”, “Magic”, “The Hunchback of Notre Dame” and “The Bunker”. I’ll see any movie with him in it, even if most of it is a steaming pile of crap. I don’t mind because I always love his performance.
Bill Paxton (swoon), and yes, I’ve seen Mortuary.
James Woods, Ed Harris, Gary Sinise, recently, Gabe Jarrett (Mitch in Real Genius).
Apollo 13 was great for me.