硫胺（英语：Thiamine），又称维生素B₁、维他命B₁，命名为「thio-vitamine」（含硫维生素）。分子式C₁₂H₁₇N₄OS。它是人体必需的13种维生素之一，是一种水溶性维生素，属于维生素B族，它最终被指定了通用描述名称维生素B₁。其磷酸盐衍生物参与许多细胞过程。最好形式是焦磷酸硫胺素（TPP），是糖和氨基酸的分解代谢的辅酶。在酵母中，TPP中也是酒精发酵的第一步骤。有保护神经系统的作用，还可以促进肠胃蠕动，提高食欲。稳定且非吸湿性硝酸硫胺盐是用于面粉和食品的营养强化同效维生素。硫胺是列在世界卫生组织基本药物的名单中，这是基本医疗卫生制度中最重要的药物名单。

Thiamine, thiamin, or vitamin B₁ (/ˈθaɪ.əmᵻn/ THY-ə-min), named as the "thio-vitamine" ("sulfur-containing vitamin") is a vitamin of the B complex. First named aneurin for the detrimental neurological effects if not present in the diet, it was eventually assigned the generic descriptor name vitamin B₁. Its phosphate derivatives are involved in many cellular processes. The best-characterized form is thiamine pyrophosphate (TPP), a coenzyme in the catabolism of sugars and amino acids. In yeast, TPP is also required in the first step of alcoholic fermentation.