Alexei Dinoia is the secondary antagonist in Tales of Vesperia.
He was voiced by Jurota Kosagi in the original Japanese version, D.C. Douglas in the English dubbed version of the game, and Jason Douglas in the English dubbed version of the film.
In the story, Alexei once won a tournament during the previous Emperor's reign and became an Imperial Knight as a reward. While rising in ranks, he grew to be accepted by many knights (including Schwann Oltorain; once born as Damuron Atomais), and the townspeople. Overtime, he discovered the true natures of Blastia and the Imperial family and used the information to help with his dream.
However, he became obsessed with changing the world after witnessing several injustices. To purge the world of its "scum", he sought to unleash a calamity into the world. During the Great War, Alexei gave fallen soldiers blastia that would replace their hearts; such as Yeager and Schawnn (who later called himself "Raven") in order for them to do his bidding.
Alexei often tried to seize control of the Dein Nomos and even tried to lure Duke Pantarei inside Baction, the Forgotten Shrine. Prior to this, he reveals that he was the mastermind behind the heinous actions of Ragou and Alexander von Cumore. He successfully used Raven to kidnap Estelliese so he would control her power as the Child of the Full Moon. Before leaving the shrine, he pinned him against Yuri Lowell's group for a battle to the death.
Alexei deployed a massive battleship called the 'Heracles' as a diversion for him to operate on top of the captial's castle. The power caused an Aer sickness that grew unusual plants and made monsters more hostile. He even forced Estelle and Yuri to fight each other.
Atop Zaude, he was confronted while trying to figure out the formula to make the Enduring Shrine work. This caused the Adephagos to accidently get summoned. Alexei was killed by Yuri and he, with a tear flowing out of his left eye, called himself "the greatest fool of all".