Casey and Andy

Casey and Andy (stylised as Casey & Andy, or simply C&A) is a webcomic series written and illustrated by Andy Weir. Following the adventures of two mad scientists (fictionalized versions of Weir himself and his best friend Casey Grimm) and of their friends and acquaintances (such as writer Jenn Brozek), it was typically updated three times a week, on Mondays, Wednesdays, and Fridays throughout the early 2000s, primarily with a gag-a-comic format, including ongoing storylines and running gags.

The comic has a strong flavor of science and history fact, often from obscure sources, as well as featuring strong parallels between Weir's and Grimm's actual lives and the events in the comic. Some strips are inspired by then-current events, such as with the Opportunity mission to Mars, the 2003 invasion of Iraq and the 2004 United States presidential election. The strip was turned made into a roleplaying game titled GURPS Casey and Andy for the GURPS system by David Morgan-Mar in conjunction with Weir, its PDF sourcebook being published by Steve Jackson Games, inspiring a "Casey & Andy approach" to death in the MMORPG genre.

On 1 May 2006, Weir announced that the strip would come to an end on Strip 666, due to Weir's recent dread for creating each strip to standard and of the potential for a downturn in the quality of the humor, and also so he could devote his time to Cheshire Crossing, his new webcomic project. Casey and Andy concluded with its 666th strip on 25 August 2008. The character of Bob was later featured in Weir's 2017 novel Artemis.

On 31 December 2021, a Casey and Andy subreddit, created and overseen by David Morgan-Mar, Casey Grimm, and John Gillman, with Weir's approval, was created for the social news and discussion website Reddit, publishing an official crossover comic with the Tredlocity science fantasy webcomic Val and Isaac, starring the character of Space Dread, in January 2022, along with an authorised offline-accessible Mega archive of the webcomic.