Hi Keri,

Yes they have. Stellar spots can even be so large that they cover half of the visible disk of the star. One of the ways stellar spots are detected by changes in the light output from the star as it rotates. The presence of spots on other stars indicate that the star has magnetic fields a bit like the Sun and by comparing their behavior with that of the Sun we can get a better idea of how stars generate magnetic fields and how their activity is modulated.

Cheers - David