|Killzone 2, Killzone 3|
|Titles||Sergeant First Class|
|Age||25 (as of Killzone 2)|
|Role||Alpha Squad's second-in-command|
|Affiliation||ISA, Alpha Squad|
|Weapons||M82 Assault Rifle, M4 Revolver, M66-SD Submachine Gun|
Sergeant Tomas "Sev" Sevchenko is second in command of Alpha Squad by rank. He is the primary protagonist in Killzone 2 and Killzone 3. Younger and less experienced than the veterans Rico and Natko, he makes up for this by being a superb technical soldier, having distinguished himself in service as courageous, intelligent and highly resourceful. This caught the eye of Colonel Templar, who saw something of himself in Sev and followed his rise through the ranks, until a fatality in Alpha opened up the position of second-in-command to Rico.
Born to a solid, respectable family in the northern city of Vekta, Sev enlisted in the army against his parents’ wishes, seeing it as his duty to defend the homeland. His powerful idealism acquired a raw personal edge when members of his own family suffered during the Helghast invasion, an incident which caused Sev to take up arms again and still plagues him with nightmares.
The player controls Sev as the ISA begins their invasion into the Helghan capital city of Pyrrhus. Sev and his squad first land at the Corinth River and assist a convoy up to the Korovis Dam. They are then reassigned to assist Captain Narville in pushing their way into Visari Square. Sev goes with Garza to demolish an Arc Tower that have been disrupting landings. Sev then cotinues all the way to Visari Square and manages to secure it with the help of his squad.
Finally, he follows a convoy straight onto the Radec Academy, only to find the Visari missing. He then is forced to fight an ATAC unit alone, but manages to overcome it. Sev is then reassigned elsewhere when the ISA forces crumble under the might of multiple arc batteries. He and the rest of Alpha Squad then go to an abandoned mine to investigate a hazardous mineral which may be a unique power source for the Helghast.
While he and Rico go off to investigate the area, Natko, Garza, and Evelyn Batton stay behind but get captured by Colonel Radec, and are sent off to a refinery. Sev and Rico fight their way onto a train to the same refinery off to rescue them. They fight their way desperately onto the train, which they find out is a transport. Finally making their way to the engineers room, they stop the train at the refinery and begin hunting them down. After Sev encounters and defeats a massive Arc gun trooper, he and Rico encounter Radec, who is interrogating Alpha squad, Rico lunges out at him, but Radec escapes unharmed, not before shooting Garza. Sev manages to get transport out of the refinery, but is unable to save Garza from his gunshot wound.
Back on the cruiser he started the game on, Garza's funeral is interrupted by a massive counterattack on the cruisers led by Radec. Sev separates from his squad to first fight off Higs at the gun deck, and then later on an AA gun shooting down hig transports. The ship suffers terrible damage, and Colonal Templar orders everyone off the ship. As Sev meets back with Rico and Natko, they manage to successfully get off ship. Not before learning that Templar has been killed by Radec, although once on ground in Helghan, they witness the falling cruiser crash into the petrusite grid, giving the ISA an opportunity to invade.
Alpha squad continue through the crash site to Narville, who is planning a final assault on the palace. Sev gets by inside an Exoskeleton, while Natko and Rico continue in a buggy. Once they find Narville, the Helghast nuke Pyrrhus City using the "Red Dust" thermonuclear bomb Radec had uncovered the codes to on the cruiser. The explosion was far away enough that Alpha squad survives, and they use the opportunity to fight into the palace. After a long hard fight, Rico and Sev engage in a battle against Radec, whom they manage to severely wound, causing his suicide. Finally reaching Visari, Sev and Rico listen as he explains their efforts are useless, and out of anger Rico kills him. They then witness a horde of Helghast troops closing in on the palace, leaving Sev and the remaining troops stuck at the palace attempting to get reinforcements.
Six months later Tomas Sevchenko changes.During the introductory scenes of Killzone 3, Captain Narville threatens to court-martial Sev for his part in the death of Visari and even goes as far as to refer to Sev immediately afterwards as Corporal.
However, when Sev's rank is mentioned throughout the rest of the game it is always Sergeant; this may be because once they were stranded on Helghan, Narville had to reconsider the demotion due to the lack of high-ranking officers and that brought about the vital need to maintain a chain of command. It may, however, also be because "Sergeant" is a shortened name for Sergeant First Class, as evidenced by Sev generally being referred to as "Sergeant" throughout Killzone 2.
After Sev and Rico fought their way to the orbital elevator, the ISA soldiers were discouraged to continuing. Sev gave a speech to the remaining ISA soldiers about how if he would die, he wants the Helghast to go down with him. As a result, the remaining force 60 soldiers under Narville's command and Narville himself agreed to make their way to the space station and kill Stahl.
As the space battle ends, Sev fires a nuclear missile at Stahl's cruiser, destroying it and releasing the irradiated petrusite stored inside the cruiser into the Helghan atmosphere, violently irradiating the planet. Sev is able to escape the explosion onboard his hijacked strike fighter alongside Rico, and rendezvous alongside Jammer and Hooper in another hijacked strike fighter. Having escaped Helghan, destroyed the entire Helghast invasion fleet and stopped Stahl's plan to destroy Earth, Sev and his comrades began their journey home to Vekta.
Also, a deeper insight into the special link between Rico and Sev is illustrated, Sev forgiving Rico for his assassination of Visari and the two heroically rally to deny the Helghast, their natural understanding allowing them to push forward.
- He appears as a character skin for Uncharted 2 Multiplayer's "Playstation Heroes Skin Pack".
- His name implies that he is of Eastern Slavic descent.
- His ISA Service Number is 021-332-3390-99
- Sev shows skills in computer technology when he fixes the communications in the Kaznan Jungle and when he uses the computer in Stahl's facility
- For some reason in Killzone 2 in the first person point of view, Sev seems to be shorter then any other character. This is likely due to the fact that the camera places itself below the character's head.
- Both Rico and Sev seem to understand the Helghan alphabet. As elite special forces, it is likely they studied the language before taking part in the invasion of Helghan. Their knowledge was likely bolstered during the six months they spent surviving on the planet following the ISA's failed evacuation.
- Sev has a younger sister named Amy Sevchenko living on Vekta, appearing in the novel, Killzone: Ascendancy.
- On January 28, 2010, the multiplayer "PlayStation Heroes Skin Pack" was released for Uncharted 2, containing respective heroes and villains from several PS3 game titles, such as Sev and a Assault Infantry.
- Sev is based on Jake Gyllenhaal, whom he resembles, with a faux hawk. His name is also a reference to a character in Tears of the Sun, Kelly Lake (Johnny Messner), who screams "SEVCHENKO" every time on screen.