When Trident was first introduced, the first thing we see is his corpse.
Originally Trident was a mercenary criminal - actually he was three mercenary criminals. To keep from establishing an m.o. which might allow him/them to be easily tracked, three criminals shared the identity of Trident. He/they ran afoul of the Titans, and each was able to escape when a Trident faced a pair of the team ( Cyborg & Changeling, Kid Flash & Terra, and Raven & Wonder Girl). Each time, using the trident, he was able to evade capture. The real names of the three criminals were known as Sammy Jaye, "Prof", and an unknown person.
In the small talk during the battle, one of the Tridents learned that a previous Trident (Sammy Jaye) had stolen a lot more money than he had told his partners. This information was divulged to the other two Tridents and they agreed to have Sammy Jaye terminated. The two remaining Tridents slew Sammy Jaye with his own weapon and left him in the river. But once the whole Titans team was together they and were able to discuss the case they figured out that they were different people and tracked down and captured the other two.
Some time after the two surviving Tridents were imprisoned, Wildebeest, sprang the black Trident from jail as well as Gizmo , the Puppeteer and the Disruptor but the Trident (Prof.) remained incarcerated. Most of these villains were eventually recaptured by the Teen Titans.
One of the Tridents, most likely the Black Trident, has appeared as a member of Alexander Luthor Jr.'s Society in the Teen Titans/Outsiders Secret Files one-shots.
The name Trident was also used by a Starro-infected Karate Kid who claimed to be Wes Holloway, a member of the Trident Guild. However, these beliefs were due to the effects of brainwashing by Starro.
Powers & Weapons
(Note Trident = person, trident = the weapon.)
None of the Tridents have any superpowers, it all stems for the trident. Other than being sharp, ethe original tridents' prongs had a separate function. One shoots fire, One shoots ice, and the third is an image inducer, allowing Trident to become invisible, but projecting his image someplace else. Later tridents seemed to have more various functions.
It is assumed that one of the surviving Tridents was the inventor of the weapon - probably the one refered to as "Prof." But is that the current Trident? We'll have to find out when Trident takes another stab at villiany .
In other media
Trident appeared in Teen Titans TV series voiced by Clancy Brown. In this version he is the amphibious super-villain terrorized Atlantis with massive ego. He first appearance in "Deep Six " using the toxic waste to create an army of clones of himself, to force everyone in Atlantis and on Earth to submit to his supposed greatness. Aqualad and Beast Boy used Trident's own ego against him - creating a battle of the Trident clones that resulted in a cave in - which sealed Trident into a prison of his own making. Trident was later freed and recruit in the Brotherhood of Evil in "Homecoming Part II" . In "Calling All Titans", he worked with Plasmus to capture Aqualad and Tramm. They succeeded in capturing them both and Aqualad and Tramm were flash-frozen as victory trophies. Later, in "Titans Together", during the final battle against the Titans in the Brotherhood's headquarters, he was defeated by Thunder and flash-frozen along with all the other members of the Brotherhood of Evil.