S4 (disambiguation)

S4 may refer to the following:
==Canon==
*Essfour, an R5 series astromech droid of the Rebellion
==Legends==
*S4-C8-GE3, a GE3-series protocol droid who operated on Nar Shaddaa
*S4-E Support Droid, a probe droid of the Order of Revan
*The S40K Phoenix Hawk-class light pinnace, the Firespray-31-class patrol and attack craft's predecessor
*The Kubrai-class S4 transport, an expensive transport ship by Kubrai Transportation