Answer
Ma Dai killed Wei Yan. Wei Yan was a general under Liu Bei during the Three Kingdoms period. After Liu Bei's death, Wei Yan became a subordinate of Zhuge Liang. However, Wei Yan was arrogant and often clashed with Zhuge Liang. After Zhuge Liang's death, Wei Yan rebelled against the Shu Han government. Ma Dai was sent to suppress Wei Yan's rebellion.