Odin Sightings

Song of Myself 1855
Odin is name-checked, along with a bunch of gods from other cultures, in Walt Whitman's Song of Myself.
The Hobbit and The Lord of the Rings 1937 - 1955
The character of Gandalf in The Hobbit and The Lord of the Rings was inspired by Odin in his Wanderer guise. J.R.R. Tolkien described the character as an "Odinic wanderer" (source: J.R.R. Tolkien, Letters, no. 107).
Marvel Comics 1962
Marvel Comics adds Odin to the Marvel universe. He shows up in the Thor and Journey Into Mystery series. He makes a great superhero.
The Sandman 1989 - 1994
Neil Gaiman's Sandman graphic novels include plenty of Norse-inspired characters, including Odin, who mostly wears his wanderer disguise.
American Gods 2001
In the novel American Gods, by Neil Gaiman, Odin appears as a character called Mr. Wednesday (Wednesday is Odin's special day).
Thor 2011
Odin shows up as an angry dad in the movie Thor. He's cast his son, Thor, out of Asgard for misbehaving.