Earn an "A" or higher rank in the indicated Mercenaries mode mission to unlock the corresponding character.

Character	How to unlock
Chris (Safari)	"The Village" mission.
Chris (S.T.A.R.S.)	"Experimental Facility" mission.
Jill (Battle Suit)	"Ship Deck" mission.
Jill (B.S.A.A.)	"Public Assembly" mission.
Sheva (Clubin)	"Ancient Ruins" mission.
Sheva (Tribal)	"Missile Area" mission.
Wesker (Midnight)	"The Mines" mission.
Wesker (S.T.A.R.S.)	"The Prison" mission.