Butyllithium may refer to one of 5 isomeric organolithium reagents of which 3 are commonly used in chemical synthesis:
- n-Butyllithium, abbreviated BuLi or nBuLi
- sec-Butyllithium, abbreviated sec-BuLi or sBuLi, has 2 stereoisomers, but is commonly used as racemate
- tert-Butyllithium, abbreviated tert-BuLi or tBuLi
- Isobutyllithium