(covers information from several alternate timelines)
The following is a list of unnamed Alpha and Beta Quadrant planetoids.
Azati Prime system planetoid
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Enterprise orbits the Azati Prime system planetoid
This planetoid was located in the unnamed star system near Azati Prime, further out from the star compared with the planet and the detection grid protecting it. It also had a single moon.
Enterprise attempted to hide behind the planetoid to avoid detection by Xindi forces in the system in February of 2154, but was unaware of the fact that there was a listening post on the moon below, staffed by three Xindi. Enterprise destroyed the outpost before it could send a message to the planet, but the lack of a report from the outpost alerted Commander Dolim of Enterprise's presence anyway. (ENT: "Azati Prime")
Diplomacy scenario 12-alpha planetoid
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The diplomacy scenario 12-alpha revolved around the mining rights for a planetoid in Nausicaan space.
Planetoid used for torpedo dissection
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View from the bridge of the Enterprise

An aerial view of the surface
In an alternate reality 2259, this planetoid with a breathable atmosphere was used by Carol Marcus and Leonard McCoy to open up an advanced long-range torpedo without endangering the USS Enterprise. (Star Trek Into Darkness)
Terikof Belt planetoids
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The Terikof belt contained several class M planetoids. In 2371, they were theorized by Tom Paris to be a possible destination of the missing ship Val Jean. (VOY: "Caretaker")