A Monument to All Your Sins is a campaign achievement in Halo: Reach. This achievement is obtained when a player completes every campaign mission in Halo: Reach on Legendary solo. It is represented by a Legendary symbol with a human skull rather than the traditional Sangheili skull.
- The achievement's name is derived from a quote from the Gravemind; "I? I am a monument to all your sins."
- Cortana says this line in a Halo 3 level, while under the influence of the Gravemind.