The fat listed in the standard French crêpe recipe along with flour, eggs, milk, and salt is butter.
Butter appears among the core ingredients of the standard French crêpe recipe. It can enrich the batter itself and is also used to grease the hot pan, helping the thin mixture spread and cook without sticking. Sugar is optional, so the same basic recipe can produce either sweet or savoury crêpes.
The recipe’s simplicity is part of what makes crêpes versatile. Flour supplies the main structure, eggs help bind the batter, milk provides liquid and tenderness, and salt sharpens the flavor. The finished batter is deliberately loose so it can flow across the pan in a very thin layer.
Once cooked, crêpes may be filled with sweet ingredients such as fruit, preserves, lemon and sugar, or chocolate-hazelnut spread. Savoury versions can contain cheese, ham, eggs, mushrooms, or vegetables. Some regional recipes use different fats or liquids, but those variations do not change the answer to this question: butter is the fat identified in the standard French formula.