Earliest Church leader and teacher outside of The Bible.
Appointed by Peter to lead the Christian community in Rome according to Tertullian. He is mentioned by Paul in Philippians 4:3. He knew the Apostles personally and would have access to a lot of eye witness testimony of Jesus and original writings himself. A every early 2nd century extra-biblical writing called
The Shepard of Hermas also mentions him. In his letter, Clement names Fortunatus, as one of the people who carry his letter to Corinth. He is named by Paul in 1 Corinthians 16:17 as well.
The only reliably known writing from him is known as 1st Clement to Corinth. A 2nd letter has his name attached but is clear it was not by him.
He was martyred around 98-100 AD.
What makes his writing and teaching so important?