Dynasty Warriors 6 has a huge cast of characters, but the majority of them must be unlocked. Here's a complete list of all the characters and how to unlock them.
Lu Bu: Clear Musou Mode with Liu Bei, Cao Cao, Diao Chan, and Sun Jian
Liu Bei: Clear Musou Mode with 3 Shu characters
Cao Cao: Clear Musou Mode with 3 Wei characters
Diao Chan: Clear Musou Mode with 1 character from each Kingdom
Sun Jian: Clear Musou Mode with 3 Wu characters
Cao Pi: Deafeat Cao Pi within 5 minutes on Sun Jian side of He Fei
Cao Ren: Succeed in Battle Objective 2 on the Lu Bu side of Fan Castle
Diao Chan: Clear Musou Mode with 1 character from each Kingdom
Dong Zhuo: Succeed in Battle Objective 1 on the Lu Bu side of The Battle of Hu Lao Gate
Gan Ning: Clear Musou Mode with 1 Wu character
Guan Ping: Succeed in 2 battle objectives on the Shu side of Fan Castle and finish battle with Guan Ping alive
Huang Gai: Succeed in Battle Objective 3 on the Wu side of The Battle of Chi Bi
Huang Zhong: Succeed in 1 battle objective on the Wei side of Ding Jun Mountain
Ling Tong: Succeed in Battle Objective 1 on the Wei side of the Battle of Shi Ting
Lu Meng: Succeed in 2 battle objectives on the Wei side of He Fei
Ma Chao: Succeed in 2 battle objectives on the Wei side of Han Zhong Attack Defense Battle
Pang Tong: Succeed in 3 battle objectives at Cheng Du battle and finish battle with Pang Tong alive
Sun Ce: Succeed in Battle Objective 1 on the Sun Jian side of the Battle of Xia Pi
Sun Quan: Succeed in Battle Objective 1 on the Lu Bu side of The Battle of Chi Bi
Taishi Ci: Defeat him in the Battle for Wu Territory
Wei Yan: Succeed in 2 battle objectives on the Shu side of WuZhang Plains and finish battle with Wei Yan alive
Xiahou Yuan: Succeed in 1 battle objective on the Shu side of Ding Jun Mountain
Xiao Quio: Succeed in Battle Objective 3 on the Wu side of the Battle of Shi Ting
Xu Chu: He Fei, Wu side, Personally kill Cao Ren and Xu Chu
Xu HuangSucceed in 2 battle objectives on the Wei/Wu side of Fan Castle
Yuan Shao: As Wei, complete all 3 targets and capture Wu Chao before completing the stage.
Yue Ying: Succeed in Battle Objective 1 on the Wei side of the Battle of Wu Zhang Plains
Zhang Jiao: Beat stage with completing all three targets in the Yellow Turban Rebellion. Playable in only Free Mode and Challenge Mode
Zhang Liao: Clear Musou Mode with 1 Wei character
Zhen Ji: Succeed in Battle Objective 1 on the Lu Bu side of the Xu Du Invasion.
Zheng He: Succeed in 2 battle objectives on the Shu side of Han Zhong Attack Defense Battle
Zhou Tai: Succeed in 3 battle objectives on the Shu side of Yi Ling
Zhuge Liang: Clear Musou Mode with 1 Shu character