General terms:
* Mwovu: This translates literally to "evil" and can be used to refer to an evil person.
* Mtu mbaya: This means "bad person" and is a more general term.
* Shetani: This is the Swahili word for "devil" and can be used to refer to a powerful evil entity.
More specific terms:
* Mtu mwenye moyo mweusi: This translates to "person with a black heart" and suggests a malicious and cruel nature.
* Mtu wa giza: This means "person of darkness" and implies a sinister or dangerous character.
* Mtu ambaye hupenda mabaya: This translates to "person who loves evil" and emphasizes the individual's enjoyment of causing harm.
Ultimately, the best way to translate "evil one" in Swahili will depend on the specific context and the desired meaning.