formidable person; someone not to be taken lightly
Refers to a person of remarkable ability, shrewdness, or presence; often used with a tone of respect or wariness.
彼は若いが、なかなかの然る者だ。
He's young, but he's quite a formidable person.
あの
a certain person; someone (unnamed)
Used when referring to a specific person whose name is withheld or unknown; often in narrative or formal contexts.
然る者から情報がもたらされた。
Information was brought by a certain person.
that sort of person; such a person
Archaic usage; now rarely encountered outside classical or literary texts.
昔話には、然る者が現れては消えるという話が多い。
In old tales, there are many stories of that sort of person appearing and disappearing.
I thought that new guy was no ordinary person, and sure enough, he turned out to be someone not to be taken lightly.
その計画は然る者によって阻止されたという。
It is said that the plan was thwarted by someone (whose name cannot be disclosed).
Standard kanji spelling for this expression.
Mixed kana-kanji spelling; commonly seen.
From classical Japanese 然る (saru, 'a certain; such') + 者 (mono, 'person'). The expression is now somewhat literary.