Asteroids in fiction
After Ceres, Asteroid 433 Eros is perhaps the most-commonly mentioned asteroid, probably because it is one of the largest near-Earth asteroids.
M-type asteroid
16 Psyche is the largest M-type asteroid, and does appear to be metallic. 21 Lutetia, an anomalous, probably non-metallic body, was the first M-type asteroid to be imaged by a spacecraft when the Rosetta space probe visited it on July 10, 2010. Another M-type asteroid, 216 Kleopatra, was imaged by radar by the Arecibo Observatory in Puerto Rico, and has a dog bone-like shape.