Question: What is the big letter at the beginning of a paragraph called?
Disambiguated questions and answers: question: What is the big red letter at the beginning of a paragraph called in medieval text ?
What is the big letter containing a picture at the beginning of a paragraph called in historical text?
What is the big letter at the beginning of a paragraph that sits inside the margins of the paragraph called?
answer: Rubricated initial
Historiated initial
Initial
Drop cap
Natural Questions answer: an initial or drop cap (from the Wikipedia article "Initial")