Archer true name is Emiya Shirou, an alternative version of the main protagonist summoned by Tohsaka Rin as her servant in the fifth holy grial war (Fate/Stay night, Unlimited Blade Works and Heaven's Feel).
He's not as the other heroic spirits, but a counter guardian who made a contract with the world to fulfill his wish to be a hero.
Some basic stats:
As an archer class servant he's able to shoot arrows from hundred of kilometers with perfect accuracy at supersonic speeds:
Low tier magic
True Mind's eye, almost impossible to speedblitz
Able to avoid Cu Cchulainn's spear after an instant teleport (almost hypersonic+ servants)
Speed: almost hypersonic+ like most direct combat servants
As a servant, he's immune to even the most advanced human weapons such as bullet and even nuclear explosions, the only way to hurt them is using strong (pure) magic and conceptual weapons. Conceptual weapons are mysteries, made by pure mana and their legends grants them power.
Can turn intangible as all servants due of his spiritual form
Managed to survive this
Enough magic resistance to escape time stop:
Standard arrows able to destroy houses (compared to a tank shell)
And can almost shoot 13 at the same time:
As a servant, even the lowest arrow has magical properties.
Caladbolg II: a reality warping weapon (probably powerful enough to oneshot Superman)
Hrunting: an arrow that travels 4km/s and is almost impossible to avoid:
Kanshou and Bayuka: close combat swords that improve his durability. Even able to deflect magic.
Rho Aias: a powerful shield that allows him to deflect even anti-army noble phantasms like Gae Bolg
Projection/tracing magic: even able to replicate materials like adamantium or kyptonite.
Tracing greatly differs from normal Projection in the fact that not only does it reproduce the shape and substance of an object, but also its entire history as well. He can also trace the physical stats of its original user. Objects created with tracing are slightly inferior to the originals due to the fact that only so much information can be gathered by sight alone, and Noble Phantasms are degraded by an entire rank. This works with Unlimited Blade Works.
Unlimited Blade Works: a pocket dimension made of unlimited blades, almost the ultimate counter of Gate of Babylon.
Even injured by Saber, he was able to kill Hercules 6 times without the Unlimited Blade Works in the Fate route.