异源生物学（英语：Xenobiology；简称XB）是合成生物学的一个分支，是合成和生物操纵生物学器件和系统的研究。异源生物学源于Xenos（希腊语）这个名词，意思是“陌生人，客人”。因而XB描述的是一种科学对其不熟悉或尚未熟悉、在自然界中也不存在的生物学形式。在实践中，它描述了新型的生命系统和生物化学，不同于经典的DNA-RNA‐20个氨基酸体系（见分子生物学中的经典中心法则）。例如， XB探索的不是DNA或RNA，而是作为信息载体，定名为异源核酸（XNA）的核酸类似物。 它还侧重于遗传密码的扩展 以及非蛋白氨基酸向蛋白质的掺入。

Xenobiology (XB) is a subfield of synthetic biology, the study of synthesizing and manipulating biological devices and systems. Xenobiology derives from the Greek word xenos, which means "stranger, guest". Xenobiology describes a form of biology that is not (yet) familiar to science and is not found in nature. In practice it describes novel biological systems and biochemistries that differ from the canonical DNA-RNA-20 amino acid system (see the classical central dogma in molecular biology). For example, instead of DNA or RNA, XB explores nucleic acid analogues, termed Xeno Nucleic Acid (XNA) as information carriers. It also focuses on an expanded genetic code and the incorporation of non-proteinogenic amino acids into proteins.