Starbase 33 was a Federation starbase that was built by Starfleet at some point in time prior to the mid-23rd century, at the planet Tarod IX in the Tarod star system. This outpost was located in the Tarod sector of the Beta Quadrant, near the Romulan Neutral Zone. The outpost consisted of a planetary settlement on Tarod IX, and a space station facility. The station resembled many Starfleet bases built in the same period, a wide circular body that tapered to a point at the bottom.
In late 2265, the starship USS Enterprise stopped off at Starbase 33 a short time after leaving Delta Vega, so that Captain James T. Kirk could be debriefed about the ship's mission to the galactic barrier by Admiral Saylor. (TOS - My Brother's Keeper novel: Constitution)
In 2364, the USS Enterprise-D was sent to Starbase 33 for standard debriefing and maintenance after an encounter at Syntagus Theluv. Having made first contact with the Creeg along the way, the Enterprise escorted a Creeg starship to the Tarod system to introduce them to a Federation delegation there. (TNG comics: "Spirit in the Sky!", "Q Factor")