In his youth Londo Mollari was an adventurer and a soldier whose family was one of the most reputable families of Centauri. He worked in the emperor's court, was a member of Couro Prido, (a fighting society where his skills earned him the name 'Paso Liati', crazed liati) and led a raid on Frallis 12. During the Earth-Minbari War Londo was the Centauri ambassador to Earth. At one point of the war he found out about the peace negotiations Delenn was organizing, mistook them for weapons dealing between the Narns and the humans and gave the order to kill all participants. By doing this he not only ruined Earth's last hope for peace, but also took the first step on his road towards damnation and the future he had seen in a nightmare. Like most of the Centauri, Londo too had seen his death in a prophetic dream. In this recurring nightmare he was killed in a hand to hand combat with a Narn. When he first met G'Kar, he immediately recognized him as the Narn of his dream.

As years went by, Londo's fame and glory began to fade. The last straw was his appointment to Babylon 5. The post of the ambassador was nothing but a joke and nobody wanted it anyway, because people believed would en up like its four predecessors. The only reason Londo accepted the job was that it took him 75 light-years away from his three wives Timov, Daggair and Mariel, whom he lovingly referred to as 'Famine', 'Pestilence' and 'Death'. In 2259 Londo managed to divorce two of his wives leaving only Timov to plague him. This wasn't his first divorce, though - years earlier an ex tempore marriage to a dancer he met in a bar had ended less than a day later due to pressure from his family.

On B5 Londo treated his job as an ambassador with the same amount of respect as the rest of the Centauri and thus spent most of his time in bars and at the casino. It was in one of those bars that he met a young dancer named Adira who reminded him of his first wife and with whom he fell madly in love. Unfortunately Adira was a slave, spying Londo for her master. When Londo found out of this, he didn't hate her, but bought her freedom and asked her to return to him one day.

Another one of Londo's pastimes on B5 was irritating G'kar, now the Narn Ambassador on B5, with any and all means he could think of, and because of this the two ambassadors were constantly at each other's throats.

In 2258 Londo met Mr. Morden, who offered him a chance to restore his fame. In return for little favours Morden's associates, the Shadows, helped Londo return a priceless artifact to the Centauri and destroy a politically inconvenient Narn base. After finding out that the Centauri Emperor Turhan was dying, Londo also allied himself with Lord Refa in order to make Turhan's nephew Cartagia their puppet emperor. Their scheming eventually led to a war between the Narn and the Centauri. Once again Londo turned to Mr. Morden and with the help of the Shadows, the Centauri were victorious. It wasn't until his friends Urza Jaddo and Malachi were killed that Londo began to suspect if the price had been too high. He feared that these powerful allies could do terrible harm to Centauri if they were to turn against them. In early 2260 finally Londo made up his mind and pulled out of his deal with Morden. Not everyone respected his decision, though. Behind Londo's back Lord Refa went to Morden and restored the alliance between the two races. Londo's attempt to scare off Refa ended badly when Morden had Adira killed and framed Refa for it. Londo revenged by having Refa killed and restored his alliance with the Shadows.

By now Londo could see the darkness ahead of him and turned to Lady Morella, Emperor Turhan's prophetic widow, for advice. She told him that there were three ways in which he could avoid the darkness: by saving the eye that does not see, not killing the one who is already dead, or if everything else fails, by surrendering to his greatest fear knowing that it will destroy him.

Ever since his deal with the Shadows Londo had been gaining power and money on his homeplanet and eventually the court began to worry. They called him back home offering him job as the advisor on planetary security and Londo accepted the post even though he knew that it was only an attempt to keep him in a leash. In early 2261 he left B5 to join Cartagia's court. On Centauri Prime he found out that it had been the Shadows who had requested him as their liaison. In return for his elevation to godhood Cartagia had sold the island of Celini to the Shadows to be used as a military base and a part of Londo's recurring nightmare came true as the Shadow vessels darkened the sky above the imperial palace. Knowing how deceitful the Shadows could be, Londo tried to make Cartagia change his mind, but the mad Emperor only cared about his imaginary ascension to godhood.

Realizing that the Emperor was quite insane, Londo turned to Vir Cotto for help and together they began to plan Cartagia's assassination. When G'Kar was captured by the Centauri, Londo bought his allegiance as well - in return for his and his people's freedom G'kar would cause distraction during which Londo could kill the emperor. Cartagia's assassination (set during G'Kar's trial on Narn) almost didn't succeed, but in the end Vir managed to poison him. With the Emperor now dead Londo became the Prime Minister and temporary leader of Centauri Prime. Londo kept his word and used his power to free both G'kar and the Narn homeworld. He then hurried back to Centauri Prime in order to free the planet from all Shadow influence before the arrival of the Vorlon planetkiller. He had Morden killed and destroyed the island of Celini, but even that wasn't enough as the Vorlon's wanted him dead too. In the end it was only the Army of Light's victory over the First Ones that saved Centauri Prime.

Even though he was the Prime Minister, Londo didn't feel safe on his homeworld and, after appointing Minister Verini as a regent to the throne, he returned to B5 with Vir. He felt that in his blind patriotism he had betrayed not only his people, but also his few friends and he very much wanted to make amends. When Captain Sheridan needed support in his war against President Clark, Londo persuaded G'Kar and the other ambassadors to join the battle. Together they also created the Interstellar Alliance, the Advisory Board of which Londo too became a member of. It was around the same time that Londo found out that the Regent was dying and that he would be the next emperor. The ensuing stress combined with the guilt he felt of his previous actions, caused Londo to have a serious heart-attack that almost killed him.

Even after his serious illness Londo continued on the road he was fated. He was supposed to return to Centauri Prime to spend some time with the Regent, but his ship was sabotaged and it was only luck that saved him this time. The assassination attempt worried Delenn so much that she ordered a bodyguard to follow him to Centauri Prime. The bodyguard was of course none other than G'Kar. Back on the homeworld there was another attempt on Londo's life, this time prevented by a mysterious alien. An alien, who Londo later found out was somehow connected to the odd behaviour of the Regent. The Regent forbade Londo to make any more inquiries of the mysterious aliens or why Centauri had started preparations for a war even though they were at peace with all the other races.

The 'why' became rather obvious when Londo was shut off the inner circle of the Alliance during the investigations of a series of mysterious terrorist acts. Even after Lennier found solid evidence of Centauri involvement, Londo continued to believe in the fact that his people had been framed. As an act of protest Centauri resigned from the Alliance and Londo returned to his homeworld in spite of Sheridan's threats that he would never be allowed back. Being a loyal bodyguard, G'kar left with him. No sooner had they arrived at the planet than the shooting war began and G'Kar was imprisoned. Londo stood by his side at first, but eventually returned to the court to find out what was really going on. He was horrified to find out that the Regent had turned off the planetary defense grid even though the vengeful Narns and Drazi were about to attack Centauri Prime.

After an attack that brought the capital of Centauri Prime to its knees, Londo was let in on the truth - the Drakh, former servants of the Shadows, were now in control, using the Regent as their puppet. They threatened to kill millions of Centauri with hidden fusion bombs if Londo did not become their new slave after the Regents death. He had no choice but to obey (though not before setting G'kar free). The Drakh killed the Regent and planted a keeper (a parasitic creature that monitors its host's every move) on Londo. He then ordered the Centauri fleet to stand down and, like the Drakh had instructed him, blamed everything on the Regent. Before his inauguration he also had time to appoint Vir as his successor on B5 and to make a speech that turned his people against the Alliance.

Although Londo was now the leader of the Centauri, he had no power at all. He was under the constant supervision of Shiv'kala, a Drakh who acted as a liaison between him and the Drakh Entire. At first Londo tried to fight back, to disobey the Drakh (he did manage to save Sheridan by warning Vir about an attempt on the President's life), but in the end he had no choice but to submit to their power. The Drakh had too strong a hold of him with the fusion bombs that were still planted around Centauri Prime and with the fact that they knew how much Londo cared for Senna, the young daughter of Lord Refa whom Londo had taken under his wings.

The Drakh no-longer wanted to kill Sheridan anyway - they had discovered another way to revenge the president's actions during the great war. Reluctantly Londo traveled to Minbar where he gave Sheridan and Delenn an ancient urn that contained a keeper very much like the one he himself had. A keeper which would take over the yet unborn David Sheridan on his 16th birthday.

The next few years saw Londo's powers diminish even more. His acts of rebellion became fewer and fewer and eventually the only thing he could do to protect his loved-ones, namely Vir and Timov, was to drive them away and to stay alone with his terrible secret. Although Londo was the only one who knew about the Drakh, he wasn't the only one controlled by them. The Drakh saw great potential the power-hungry official Durla and used him just as much as they used Londo (and with Durla they didn't even need a keeper). They helped Durla into power and that power was even more away from Londo who eventually became nothing more than a facade.

The years didn't treat Londo well. He grew old and infirm, watching his beloved homeworld succumb deeper in the darkness under the rule of Durla and the Drakh. He was already quite badly demented when the prophesies came true and the time for the final confrontations was at hand. In 2277 the Drakh took control of David Sheridan and then used the boy to lure his parents to Centauri Prime. At the same time a Centauri resistance movement called Legions of Fire and led by Vir started their final assault against the Drakh. The Drakh were defeated, but not wholly and they managed to revenge by using the fusion bombs they had hidden twenty tears earlier. Amidst the confusion Londo decided to do his part and turned to G'Kar who had spent the last few years on Centauri Prime. He drunk himself half-senseless and then asked his old friend to kill him so that the Drakh wouldn't find out that he had just set Sheridan, Delenn and David free.

It was now time for Londo to surrender to his greatest fear as he died with G'Kar's fingers around his throat. At the last moment, however, the keeper took control of him for the last time and he strangled G'Kar. Lady Morella's prophesies were fulfilled and Vir became the Emperor. The diaries Londo had written during the last twenty years to keep himself sane were eventually edited and published by Vir and the new Emperor also made sure that a statues for Londo and G'kar were erected at the gates of the Centauri capital.