In his early career,
Carlos Pacheco did some work for Planeta Comics, an imprint of pan-European publisher Planeta De Agostini, mainly covers and pinps for Spanish translated editions of Marvel Comics, published at the time by Planeta. He later teamed up with writer Rafael Marin to create the Spanish superheroes Iberia Inc and Trada Vrtice for the same publisher.
Pacheco first got attention in the United States for his work as penciller on
Dark Guard, a 4-issue Marvel UK title where he worked with writer Dan Abnett and inker Oscar Jimenez.
This led to him being offered work by American comic editors leading to Marvel Comics 1994
Bishop four issue limited series where he worked with writer John Ostrander and inker Cam Smith.
Later that year Pacheco did his first work for DC Comics on The Flash #93, 94 and 99, with writer Mark Waid and inker Jose Marzan Jr.
After that Pacheco's next stateside work came in 1995's
X-Universe two part limited series (a part of the Age of Apocalypse event), published by Marvel. Pacheco was joined by writer Terry Kavanagh and was again inked by Cam Smith. At the end of 1995 and the beginning of 1996 Pacheco and Smith collaborated with writer Warren Ellis on a
Starjammers limited series. This series was successful enough that the creative team was reunited on Marvel's
Excalibur ongoing series for a brief run in 1996. Shortly after this Pacheco became penciller on Marvel's
Fantastic Four for two issues (#415-416), where he worked with writer Tom DeFalco as the title wrapped up in preparation for Heroes Reborn.
By that point Pacheco's art had become a fan favorite, with his work regularly getting coverage in magazines such as Wizard.
In early 1997 Marvel acknowledged this by assigning Pacheco to one of its flagship titles,
X-Men, with #62 (March, 1997). On that title he worked with writers Scott Lobdell and Joe Kelly and inker Art Thibert.
He left the title at #75 in May 1998.
After X-Men, Pacheco began work on
Avengers Forever a 12-issue limited series, where Pacheco worked with writer Kurt Busiek and (for the first time in the U.S.) inker Jesus Merino, who from that point on became Pacheco's regular inker. This series, which drew together many strands from various Avengers storylines to tell an epic adventure, was a critical, fan and commercial success.