Space pirate

Space pirates were criminals who robbed ships in space.

Space pirates operated by sabotaging navigational beacons and luring spacecrafts away from chartered space routes to ambush them and steal their cargo. They were also known to claim the beacons, storing their bounty in the Bank of Karabraxos, taking advantage of its habit of not asking too many questions. (PROSE: The Whoniverse)

The Captain was a space pirate who became ruler of Zanak. (TV: The Pirate Planet)

Captain Anastas Thrax was the leader of a band of space pirates in 2075 which hijacked supply ships en route to the human colony on Venus. (COMIC: The Hijackers of Thrax)

Maurice Caven was the leader of a band of space pirates in the 22nd century which robbed argonite shipments. (TV: The Space Pirates)

The Second Doctor, John and Gillian stopped space pirates from stealing Neon's food supplies. (COMIC: Dr. Who and the Space Pirates)

A band of Lizardian space pirates led by Skanus used false distress calls to lure in ships and then rob them. (COMIC: Jackals of Space)

Kari and Olvir were space pirates who mistakenly boarded a ship transporting victims of Lazar's disease to Terminus. (TV: Terminus)

Because it had a dilapidated and deserted appearance, the Seventh Doctor and Mel thought toll port G715 had been attacked by space pirates. (TV: Delta and the Bannermen)

Lisa Deranne initially mistook the Sontarans, including Commander Steg and Lieutenant Vorn, for pirates until Kurt identified their work as military and revealed their identity. (HOMEVID: Shakedown: Return of the Sontarans)

Hamlek Glint was a space pirate who had an all-robot crew. (PROSE: The Resurrection Casket)

The Starship Brilliant was attacked by space pirates. (PROSE: The Pirate Loop)

Baltazar was a space pirate in the 40th century. (TV: The Infinite Quest)

In the 41st century, Abigail Crane hired space pirates to test out Merrick Kingdom's samples of varga venom on workers at a spaceport. (AUDIO: The House of Kingdom)

Seruba Velak's ship was shot down by space pirates. (TV: Dreamland)

Cornelius was a pirate captain in the far future. (PROSE: The Coming of the Terraphiles)

Despite all this, space piracy was actually extremely rare due to it being unprofitable; the pirates who did operate were in it purely for the thrill. (PROSE: Mission: Impractical)

Information from invalid sources
The Seventh Doctor would encounter space pirates again at the same time as a data vampire in his Earth Aid adventure. (PROSE: What If?)