- Red spiders (with six legs) were a recurring theme in early xkcd comics.
- They appear in at least 7 different comics, although they are no longer shown regularly. The last comic where they were mentioned was 1110: Click and Drag, in September 19, 2012.
- The picture shown here is not representative of the spiders, as the other versions of the spiders are more pink than red.
- In the last comic so far 1110: Click and Drag they are even black and white, but can be recognized by their six legs.
- In 47: Counter-Red Spiders there are no Spiders, but they are mentioned by name and that comic is part of the original series, which comprises the first four listed here below.
- Red spiders are also shown in the XKCD book volume 0 on the back cover.