Cajal is a tiny lunar impact crater on the northern part of the Mare Tranquilitatis, in memory of the Spanish doctor and Nobel laureate Santiago Ramón y Cajal. It is a circular, cup-shaped formation that lies to the southeast of the lava-inundated crater Jansen. Cajal was formerly designated Jansen F, prior to renaming by the IAU. Also to the northwest is a system of wrinkle ridges designated the Dorsa Barlow.
- Santiago Ramón y Cajal, Spanish histologist, physician, pathologist
- Fortún Garcés Cajal, medieval Spanish nobleman
- Nicolae Cajal (1919–2004), Romanian Jewish physician, academic, politician, philanthropist
- Cajal Institute, a neuroscience research center in Madrid, Spain.
- Cajal–Retzius cell
- Interstitial cell of Cajal (ICC)
- Cajal bodies (CBs)
- Cajal (crater), a tiny lunar impact crater