Throughout the rest of the century, Prester John appeared sporadically in pulp fiction and comics. For example, Marvel Comics has featured "Prester John" in issues of "Fantastic Four" and "Thor". He was a significant supporting character in several issues of the DC Comics fantasy series "Arak: Son of Thunder". Charles Williams, a member of the 20th-century literary group the Inklings, made Prester John a messianic protector of the Holy Grail in his 1930 novel "War in Heaven". Prester John and his kingdom also figure prominently in Umberto Eco's 2000 novel "Baudolino", in which the titular protagonist enlists his friends to write the "Letter of Prester John" for his adoptive father Frederick Barbarossa, but it is stolen before they can send it out.