A person with no empathy or very limited capacity for empathy is often described as a "psychopath" or a "sociopath." It's important to note that these terms are not official medical diagnoses, but rather informal descriptions used in common language and popular culture to refer to individuals who lack empathy and have difficulties understanding or relating to the emotions of others.
In clinical settings, professionals may use terms like "antisocial personality disorder" or "narcissistic personality disorder" to describe individuals with limited empathy, but it's essential to rely on proper assessment and diagnosis by qualified mental health experts rather than making assumptions based on labels alone. These conditions involve complex psychological traits and should be treated with sensitivity and understanding.