The origin of Impulse (also known as Pulsar) is largely unknown except that he has been a long time member of the Shi'ar Imperial Guard and has fought alongside them for many years. He is made up of pure energy and his form is only because of his suit he wears.
Impulse was created by Chris Claremont and Dave Cockrum in 1977 and first appeared in The (Uncanny) X-Men Vol. issue 107 (1977).
Major Story Arcs
With the Imperial Guard
Impulse was present during a number of large battles against other species, most notably against the X-Men and later against the Phoenix. He was also present during Operation Galactic Storm.
Seeming Death, Revival and Wedding Crasher
He was seemingly killed in battle with Vulcan. However, Impulse recently appeared fighting alongside the rest of the Imperial Guard in an assault on the Kree-Inhuman wedding of Ronan the Accuser and Crystal. Impulse brutally wounded the Inhuman elite warrior Gorgon during the battle.
Impulse, alongside the other Imperial Guard managed to defeat (an already weakened) Thanos, after which they brought him to a Shi'ar prison.
Age of Apocalypse
As in the regular Marvel 616 universe, Impulse was a member of the Imperial Guard in this alternate reality. Along with Gladiator and the rest of the Guard, he confronted Gambit and the X-Force, mistaking them for enemies when they teleported to the M'Kraan Crystal. With the help of Rictor, Impulse and the Guard attempted to capture the mutants, only to be killed by the M'Kraan's expanding crystal wave while Gambit and his team escaped.
It is not known what alien race Impulse belongs to. He is kept within a containment suit to keep his energy output in control and also focus his energies into a concussive blast that eminates from his visor. He also can fly with the use of a "flight belt".