Idris is traditionally considered the first prophet to write with a pen. This attribution comes from Islamic tafsir and prophetic-story literature rather than from an explicit Quranic statement that he invented or first used writing.
The Quran identifies Idris as a truthful prophet and says that Allah raised him to a high station in 19:56–57. Classical commentators expanded this brief portrait, associating him with writing, wisdom, astronomy, and the establishment of weights and measures. Ibn Ishaq is traditionally credited with the account that Idris was the first person to write with a pen.
Idris is often identified in Islamic tradition with Enoch, a figure from the biblical lineage of Adam. That identification is widespread but not stated by name in the Quran. Another common mistake is to present the pen tradition as settled history; it is best described as a longstanding religious tradition, which is exactly why the question’s word “traditionally” matters.