Fiend-like is a strong and powerful term used to describe someone who is maliciously wicked and evil. To find synonyms for fiend-like, one might consider words like demonic, diabolical, evil-minded, malevolent, Satanic, wicked, or nefarious. These words emphasize the particularly intense degree of wickedness and evil that the term fiend-like implies. Other synonyms include vicious, ruthless, and inhumane, all of which convey a sense of cruelty and callousness. Whether looking to describe a sinister character in a story or simply to emphasize the degree of evil being encountered, these synonyms can help add depth and color to writing.