public enemy number one

US dated uncountable broadly idiomatic

(US, law enforcement, dated) A person who ranks highest on the federal government's prioritized list of wanted criminal fugitives.

Japanese Meaning

連邦政府の指名手配リストで最も優先される対象となっている犯罪者。 / 当局にとって最重要な犯罪者と位置付けられる人物。

After months on the run, the FBI finally captured the suspect who had been labeled public enemy number one.

数ヶ月にわたる逃亡の末、FBIは連邦政府が最も捜索していた最重要指名手配者の容疑者をついに逮捕した。

Sense（1）

(US, law enforcement, dated) A person who ranks highest on the federal government's prioritized list of wanted criminal fugitives.

Sense（2）

(idiomatic, by extension) A person, organization, or other object considered to be particularly menacing, harmful, or loathsome.