Thief
A thief was a type of criminal who engaged in the crime of theft; where specific terms were also used to described thieves of various sorts: 

 One who steals from a premises was known as a burglar.
 One who steals from a premises by breaking and entering through an upper level story, analogous to a cat, was known as a cat burglar.
 One who steals during a war or riot was known as a looter.
 One who steals items of low monetary value was known as a petty thief.
 One who surreptitiously steals an item from another person's body was known as a pickpocket. 
 One who specifically stole cattle was known as a cattle rustler. 
 One who steals with the threat of or use of violence was known as a robber.

Examples 
In 2063 of the mirror universe, upon first contact with the Vulcans, the  was boarded and looted following the murders of its crew. ()

In 2263 of the alternate reality, the leader of the Teenaxi Delegation insisted to Captain  that the Fibonans were "a crowd of untrustworthy thieves" who had stolen a piece of the Abronath before gifting it to the Teenaxi. ()

Captain Kirk pick-pocketed keys from an Ekosian corporal in 2268. ()

Em/3/Green was a master thief and a lockpick. ()

Shortly after the Federation takeover of Deep Space 9 in 2369, Odo accused Quark of being a thief and a gambler. Quark denied the thief accusation and added that even he were one, Odo hadn't been able to prove it for four years. ()

Later that year, Odo called the Rakhari Croden a killer and a thief. ()

Again that year, a Dopterian pickpocket stole several items from patrons in Quark's, including Lwaxana Troi. Constable Odo later told Commander Benjamin Sisko that he knew how to handle killers and thieves, but not Lwaxana Troi. ()

In the  holoprogram, Worf accused the character of Eli Hollander of being a thief, prior to his arrest. () 

In 2371, Quark accused his brother Rom of being a thief after Quark discovered missing items from his bar in Rom's quarters. ()

Also that year, while visiting a holographic recreation of Chez Sandríne in Marseille, Tom Paris told Harry Kim that, years earlier while stationed at the Marseille Starfleet base for training, he discovered the bar shortly after his pocket was picked near the harbor. Kim expressed shock that such criminal activity had occurred on Earth, but Paris reassured him that "they just do it for tourists. They give it back. Most of the time." ()

Trelos Vren once tried to break into Deep Space 9's assay office, and in 2372, tried to take up pick-pocketing. ()

Razka Karn was a smuggler, thief and black marketeer, with at least twelve outstanding warrants for his arrest on Cardassia as of 2372. ()

Garak was skilled at pick-pocketing. ()

The movie To Catch a Thief involved cat burglars. In an alternate 2374, Harry Kim gave this term as a clue when trying to get B'Elanna Torres to name the movie and its male lead. ()

See also 
Looter
Pirate
Robber

External link

de:Taschendiebstahl
Illegal occupations