There are so many labels in the world today to describe the word “evil” . In psychiatry, 2 diagnoses are frequently used to describe such evil; narcissistic personality disorder and anti social personality disorder.
In psychiatry, psychopathy and sociopathy are terms that are sometimes used but not in fact, placed in the current DSM.
A person can lack capacity to empathize but that does not make a person evil. People can love themselves but not be evil. What makes a person evil is how those particular traits are applied within one’s life. If a person is selfish because they ONLY care about themselves, evil is the result. If a person lacks the capacity to empathize and also feels gratified when other people are suffering, this leads to evil as well.
Everything comes down to intent. When a person holds ill intent towards another human being and acts on such intent, they are evil. People want to call evil psychopaths and sociopaths but in the end, its the intent of behavior and desire that describes true evil.