At least two classes of frigates have been named Thetis after their lead ship:
- Thetis-class frigate, a pair of steam frigates built for British Royal Navy in the 1840s and then sold to the Prussian Navy
- Thetis-class patrol vessel, three patrol vessels of the Royal Danish Navy built in the late 1980s and early 1990s
This article includes a list of ships with the same or similar names. If an internal link for a specific ship led you here, you may wish to change the link to point directly to the intended ship article, if one exists.