"C'mon, hot shot pilot, we made it. Nice bit of flying you did, there."
- – Michael Garibaldi
Warren Keffer was a Human male, who by 2259 was stationed on Babylon 5 and was a member of Zeta Wing under Zeta Leader Ray Galus. Early in 2259, Captain John Sheridan, a hero of the Earth-Minbari War, took command of Babylon 5. Shortly after his appointment, the Minbari warcruiser Trigati, the crew of which refused to surrender at the end of the war and held a grudge against Sheridan, came out of hiding. The crew hoped they could force Babylon 5 to destroy them, allowing them to have some honor in death and perhaps even reignite the War. Keffer was involved in the standoff with the Trigati until Sheridan sensed he was being set up and refused to fire on the ship, calling on another Minbari cruiser instead. The Trigati was asked to surrender, but the crew set the ship on self-destruct. 
Soon thereafter, Babylon 5 received a distress call from a ship in grid epsilon. Keffer and Zeta Wing were dispatched to investigate, and they found the ship adrift with all its crew, except for one, dead. The ship was subsequently taken to Babylon 5.
Later, when criminal Jason Colby took Colonel Rabock—in reality, telepath criminal "Cypher"—hostage and tried to escape on a shuttle, Zeta Wing was scrambled to intercept them. However, the shuttle exploded from the inside as a result of a scuffle aboard between the two criminals.
When the explorer ship, the Explorer class ship EAS Cortez was lost in hyperspace, Keffer was one of Zeta Squadron's pilots that participated in its search. Sheridan formulated a rescue plan, the key point of which was to create a chain of ships, so that each Zeta member was in range of the previous squadmate and this way avoided being lost. Such method was successful and the Cortez was found. However, a strange black starship suddenly appeared. Zeta Leader Ray Galus and Keffer, who were concluding the chain, collided with it. Galus died, but Keffer was lucky enough to survive, although his Starfury was badly damaged and began drifting in the hyperspace with no communication. With no other way to guide the Cortez back to Babylon 5, Keffer began shooting at the direction of the exit gate. Cortez's captain Jack Maynard understood Keffer and the Cortez returned safely along with the rest of Zeta Squadron. Keffer was presumed killed in action with Galus.
Keffer soon regained control of his ship, but the exit gate's signal was lost. Suddenly, the same strange object appeared. Thinking that it might have been traveling along the same course where Babylon 5 was, Keffer followed the ship and soon returned to the station. There, he was greeted and asked to become the new Zeta Leader. Keffer accepted the offer and soon reported about the mysterious ship. However, since his recording machinery was not working at the time of this encounter, he had no evidence to prove what he had seen. Following this, he became determined to find out what the spacecraft really was.
Later that year, Keffer was doing some routine maintenance work in the hangar bay when he spotted Security Chief Michael Garibaldi trying to sneak aboard one of the ships. Garibaldi, suspecting Centauri Ambassador Londo Mollari's involvement in the destruction of a Narn outpost in sector 37, had began spying on Londo. After learning that the latter was planning a meeting with Lord Refa, Garibaldi had decided to beat him to the rendezvous point and spy on the Ambassador. Keffer offered to pilot the ship and fly Garibaldi to his destination. When the two of them emerged from a jump gate near the planet where Londo was supposed to arrive, Garibaldi began telling Keffer the story of his meeting with Commander Jeffrey Sinclair—the previous commander of Babylon 5—in an attempt to kill some time. Garibaldi told Keffer how Sinclair hired him as a pilot on Mars. He did not have the time to finish, though, as a vessel similar to the one Keffer had seen in hyperspace appeared and shot their ship down, and Keffer had to crash-land it on the planet.
Their transmitter broken in the crash, the two decided to go to a nearby Centauri settlement and ask for help. On their way, Garibaldi continued his story, telling Keffer how he once crashed his shuttle while on a mission with Sinclair and how they subsequently ventured off to find help. When Keffer and Garibaldi scaled a mountain, they witnessed the mysterious ship landed on the other side and its complement embarking on the search for them. The two sped up, hoping to leave their pursuers behind.
When they reached a clearing in the surrounding jungle, Keffer began to suspect that their predicament was in fact set up by Garibaldi who was allied with the attackers. Unbeknowst to Keffer, his mind was being affected by the aliens who were pursuing them, who were telepaths. Keffer forced Garibaldi to drop his PPG and then fired his own weapon at him, but Garibaldi ducked and Keffer hit one of the aliens instead, severing the telepathic link. After he came to his senses, Keffer threw Garibaldi's PPG back to him and the two of them killed the remaining enemies, whose bodies evaporated after death. Now that they were safe, Garibaldi finally reached the most interesting part on his story—while looking for help on Mars, he and Sinclair had found a similar looking mysterious ship.
There was also a facility established near that ship, which Garibaldi and Sinclair had infiltrated. Upon discovering that experiments were conducted on people there, they had destroyed the facility. Just as Garibaldi finished his story, he and Keffer were taken into custody by the local Centauri, on the charges of spying. The head of the settlement contacted Londo on Babylon 5 in an attempt to prove that Keffer and Garibaldi were allowed to be in the Centauri space. If Londo would not confirm that, the two would be executed. Instead of Londo, his aide Vir Cotto responded to the call. Claiming that Londo was unavailable, Vir lied that the two officers were permitted to be in that sector of space. However, Londo soon answered to the transmission. Keffer's and Garibaldi's lives were in Londo's hands, who, much to the two Humans' relief, backed Vir's words. The two were released and returned to Babylon 5.
While Babylon 5 became a party to 25,000 GROPOS, Keffer was forced to share his quarters with two marines, Large and Yang. While Keffer was initially frustrated with such conditions, the three soon became good friends. Unfortunately, both marines were killed in Operation Sudden Death on Akdor shortly thereafter.
Short time later, an unidentified object was spotted near Babylon 5 and Keffer was sent to investigate. It turned out that the object was just a teddy bear—a toy which had been made for the Babylon 5 fair to portray John Sheridan, and which had been spaced out by Sheridan himself. Smiling, Keffer did not reveal what the object was, reporting only that it was harmless.
Keffer used much of his off-duty time looking for the mysterious ship that he had encountered in hyperspace. When this became known to the command staff, Keffer was ordered to stop.
When a Markab transport vessel was delayed beyond an appointed time and was not responding to Babylon 5's calls, Zeta Wing was sent to investigate. Keffer and his group soon found the ship drifting in space with the entire crew dead, killed by the "Drafa Plague which soon wiped out the entire Markab species.
Keffer soon received a word that one of Delta Wing's pilots, Mitch Harvey, had also seen something in hyperspace. Keffer told Mitch about his own encounter and was warned by him not to try to find the vessel. However, Mitch gave Keffer his data crystal with some readings on the mysterious ship.
That same year, a war between the Narn Regime and the Centauri Republic occured. The Narns were defeated and their military forces were almost decimated. One Narn ship requested sanctuary near Babylon 5 and Sheridan agreed. However, the Centauri soon learned about it and demanded that the ship be given to them, to which end they sent a battlecruiser. Sheridan refused and the Centauri began targeting the Narn ship. Since that ship was undergoing repairs and thus could not defend itself, Zeta Wing was called to assist. While Babylon 5 fought the Centauri cruiser, Keffer's squad escorted the Narns through hyperspace to safety.
Keffer soon picked up a signal similar to the one that Mitch had given to him and set off alone to investigate. Keffer was finally successful in his quest as he saw the same black ship. He managed to record it and dump that footage before the ship attacked and killed him. The footage from his ship was found and released on the ISN soon afterward.
Despite the ultimate price that Keffer paid for this evidence, the footage was shortly removed from syndication.
Keffer apparently had a wife or a girlfriend back home, from whom he received holographic messages. 
- "Points of Departure"
- "A Distant Star"
- "There All the Honor Lies"
- "Confessions and Lamentations"
- "The Fall of Night"
- "Matters of Honor" (Mentioned only)
- "The Price of Peace"
- "With Friends Like These"
- "Against the Odds"
- "Survival the Hard Way"
- "Silent Enemies"
- ↑ 1.0 1.1 Points of Departure
- ↑ "Treason"
- ↑ "The Price of Peace"
- ↑ 4.0 4.1 A Distant Star
- ↑ "With Friends Like These"
- ↑ "Against the Odds"
- ↑ "Survival the Hard Way"
- ↑ "Silent Enemies"
- ↑ GROPOS (episode)
- ↑ There All the Honor Lies
- ↑ 11.0 11.1 Confessions and Lamentations
- ↑ 12.0 12.1 12.2 The Fall of Night
- ↑ Matters of Honor
|Main Characters (Babylon 5)|
|Commander Jeffrey Sinclair Captain/President John Sheridan Lt. Commander/Commander Susan Ivanova Security Chief Michael Garibaldi Ambassador Delenn Dr. Stephen Franklin Talia Winters Lennier Marcus Cole Captain Elizabeth Lochley Vir Cotto Lieutenant Warren Keffer Na'Toth Security Chief Zack Allan Lyta Alexander Ambassador/Citizen G'Kar Ambassador Londo Mollari|