The death penalty is the state-sanctioned execution of an individual or party.
Starfleet's General Order 7 had execution as a punishment for traveling to Talos IV. (TOS: "The Menagerie, Part I", "The Menagerie, Part II")
The Cardassian Union had the death penalty. (DS9: "Tribunal")
The Dominion utilised the death penalty, including summary execution. (DS9: "Sacrifice of Angels", "What You Leave Behind")
In an alternate universe where the Dominion won the Dominion War, Rom was executed for his attempt at sabotage of Terok Nor. (TFS: Spectrum: "The Final Prophecy")