OK, only the head and the voice belonged to Billy Crudup; the rest of the blue hero's physique belonged to a professional bodybuilder. Still, Crudup provided the movements for the nuclear-powered mutant who tried in vain to seem like one of the gang.
In Robert Zemeckis's second all-motion-capture movie, leave it to the often weird Crispin Glover to make a sympathetic monster out of Grendel, a misshapen mama's-boy who looks like the "Eraserhead" baby grown into a skeletal adult.
Mark Ruffalo is the first Hulk portrayer to play both Bruce Banner and his green, raging alter ego, and it makes a difference. His is a Hulk you can cheer for, since you can recognize the tormented scientist inside.
In the best of Robert Zemeckis's motion-capture movies, Jim Carrey makes an impeccable Ebeneezer. There's no trace of Carrey-ness in his voice, his face, or his movements; its as completely immersed in a character as Carrey's ever been.
Zoe Saldana had to make you believe Jake Sully (Sam Worthington) would not only fall in love with a tall blue feline woman from another species, but that she was so worthy that he'd leave his own species to become a Na'vi. Mission accomplished.
Andy Serkis teamed up with "Lord of the Rings"-master Peter Jackson again to play one half of cinema's most famous ill-matched couple. Besides convincingly making a monkey out of himself, Serkis gave Kong enough soul to make it clear why his tiny human captive, Ann (Naomi Watts), would come to care for him so deeply.
Toby Jones gave the house elf both mischief and pathos. As annoying as he is in his first movie, he's so moving by the time he breathes his last that you'll be sobbing over his computer-generated remains. Now, that's acting.
Andy Serkis's crowning achievement is still the one that put him on the motion-capture map -- and made everyone else realize that motion-capture was capable of creating movie characters with real soul. Or two conflicting souls, in Gollun's case, one happy to help the hobbits on their quest to destroy the ring, and one that would stop at nothing to possess the "precious" again.