Radagaisus (died 23 August 406) is a Gothic king who leads an invasion of Roman Italy in late 405 and the first half of 406.

A committed pagan, Radagaisus evidently plans to sacrifice the Roman Senators to the gods and burn Rome to the ground.

Radagaisus is executed after being defeated by the half-Vandal general Stilicho.

12,000 of his higher-status fighters are drafted into the Roman army and some of the remaining followers are dispersed, while so many of the others are sold into slavery that the slave market briefly collapses.

These Goths later join Alaric I in his conquest of Rome in 410.