Heroes & Villains of the 41st Millennium is a White Dwarf feature covering five named characters, each given a short profile plus (for three of the five) a playable rules box. The other two — Ahriman of the Thousand Sons and Fabius Bile — carry no rules content in this feature. Each of the three with rules also has its own entry in a Codex; see the cross-link on each page below.
Heroes & Villains of the 41st Millennium
Source: Heroes & Villains of the 41st Millennium, p. 1