Dateless Grave

Gravestones in TV and films tend not to have full dates on them, unlike in real life. Presumably this, like so many other tropes, has to do the perception that, with movies being shown on TV and released on home video, they need to be "timeless" and not pinned to a specific date.

This trope also applies to newspapers (on a larger scale).

Comic Books

 * Ubiquitous in comics. The X-Men have an entire cemetery full of dateless graves. However, it was averted when Jean Grey "died" for the first time—her original lifespan was 1956 to 1980 (making her 24 when she died the first time), if you were wondering.
 * Granted, it would be awkward to have a bunch of graves with a series of dates written on them for each successive death and return.

Film

 * The 2007 police comedy Hot Fuzz, especially the Sandford newspaper.
 * In fact, the movie's time period is pinned down. Nicolas asks a clearly under-aged kid in a bar his birthday. The kid says 8 May 1969, to which Nick replies, "So you're 37?" Which puts the movie in 2006, or early 2007.

Literature

 * Avoided in Harry Potter. For the first time in his life, Harry visits his parents' graves in Godric's Hollow, and the dates on the gravestones are practically the only place in the whole series where specific years are given. This heightens the emotional impact of the scene considerably. (The only other bit of dating evidence is from Chamber of Secrets, on Nearly-Headless Nick's deathday cake, which, appropriately enough, is tombstone-shaped.) We can date the series from 1991-1998.
 * In the third The Dresden Files novel, Harry is given a grave and gravestone by one of his (many) vampire nemeses. The gravestone has no date but reads "Harry Dresden - He died doing the right thing"

Live Action TV

 * The Bill
 * Sherlock's grave gives only his name. It's a damn classy gravestone, though.
 * Star Trek the Original Series: The grave marker created by Gary Mitchell in "Where No Man has Gone Before".
 * The use of Stardates helped hide the time line during the run of the show. Years were attributed to events as the Movies and Sequel Series came out.

Video Games

 * The Boss' gravestone in Metal Gear Solid 3: Snake Eater reads "192X-1964"
 * Averted in Left 4 Dead 2, where graffiti in the safehouses has the birth and death dates of various people, pointing that the game is set in 2009. Banners hanging in the mall further show that the game is set in fall of 2009, at around the time it was released.

Webcomics

 * The lost Heterodyne heir's grave in this page of Girl Genius. Although it's not so much to stop the comic from becoming dated as to make sure we don't know what century this steampunk parallel Europe is set in.
 * Though the grave does have a year-of-birth and the number of days he lived. There is just something in the way to keep us from seeing what century that year was in.
 * Angelica's grave in Misfile is dateless and surname-less as well.
 * In Kevin and Kell, Corrie visits her mother's grave, and in the only panel showing the dates on the grave, her hand is blocking the last two digits of the year of death, although it is shown that her mother was born in 1968. The strip never makes any explicit reference to what year it is, except for the Y2K arc being set in late 1999.
 * In The Order of the Stick, Elan does not put a date of birth on Therkla's grave, as he does not know when she was born, although the date of death sets the story in the year 1184, according to whatever calendar they're using.
 * Which fits with the dates given on the deva's Belkar-evilness-over-time graph.

Western Animation

 * Justified in Justice League, wherein Hawkgirl tries to bury Solomon Grundy according to Earth's customs, but only knows that he was "Born on a Monday."