Stoicism is a school of ancient philosophy founded in Athens by the the merchant Zeno of Citium in 301 BC. It was first called Zenonism but came to be known as Stoicism because Zeno and his followers met in the Stoa Poikilê, or the Painted Porch.
The Stoics would meet outside in the public, on this porch, and anyone could listen to the debate. It was a "street philosophy" for ordinary people.
Since the onset and for nearly five centuries Stoicism is still one of the most influential and highly-regarded schools of philosophy. This may be because of how practical it is.
Recently since the 1970s that Stoicism has grown in popularity again. Mainly because it’s been the philosophical inspiration for Cognitive Behavioral Therapy (CBT)
Called "The Last Good Emperor" of the Roman Empire. Was most powerful man on earth, and still sat down each evening to reflect on the day and write down in his private diary. This private diary has been published as the book Meditations and it is said to be one of the most influential stoic books.
On the other extreme Epictetus was born a slave. After gaining his freedom, he founded his own school and taught many of Rome’s greatest minds, one of which was Marcus Aurelius.
Tutor and adviser to Nero (who later committed Seneca to death). Many of his personal letters survived and serve as a great source of Stoic philosophy. These are commonly known as "Letters to a Stoic"