Issue #6 (top left): Titled "Invasion," it features Magneto on the cover and is the conclusion to the first major arc of the series.

Issue #7 (top right): Titled "Return to Weapon X," this issue begins the second story arc where the X-Men are forced into the Weapon X program.

Issue #8 (bottom left): Also part of the "Return to Weapon X" arc, the cover features Storm.

Issue #9 (bottom middle): Continuing the "Return to Weapon X" storyline, the cover features the character Iceman.

Issue #10 (bottom right): The conclusion of the "Return to Weapon X" arc, it is titled "In the Heart of Darkness" and features several X-Men characters on the cover.
These issues were written primarily by Mark Millar, with art by Adam and Andy Kubert. They are part of the successful Ultimate Marvel imprint, which reimagined classic Marvel characters for a modern audience.