A Crayola brown from 1998
Shadow is a regular Crayola crayon. It joined the lineup in 1998 and is still made. The color is a grayish brown, a bit like dry mud or old wood.
The code here, #8A795D, matches the entry in Wikipedia's list of colors. The newer list of Crayola crayon colors gives a darker value, #837050, so the two sources do not agree.
Similar browns
Shadow is close to raw umber and pale brown. Crayola also has a blue crayon called Shadow Blue, but it comes from a different box.

