The following is a list of what is marked on the tomb stones in the beginning of the Treehouse of Horror episodes.  After a while they stopped doing these tombstone sequences, because it was costing them too much time as their episodes were cut with half a minute, but for the episodes that they are there, we have the list, thanks to Nimbus. 

Halloween Special I
*Ishmael Simpson
*Ezekiel Simpson
*Cornelius V. Simpson
*Garfield
*The Grateful Dead
*Casper The Friendly Boy
*Elvis
*Your Name Here
*Paul McCartney
*Disco
 
Halloween Special II
*Bambi's mom
*Jim Morrison (lives!) (complete with hippies)
*Cajun Cooking
*Walt Disney
*Lose Weight Now Ask Me How

Halloween Special III
*Drexell's Class
*I'm With Stupid --->
*R. Buckminster Fuller (pointed at by previous stone)
*American Workmanship (crumbles)

Halloween Special IV
*ELVIS Accept It (with loud scream)
*A Balanced Budget
*Subtle Political Satire
*TV Violence (gets shot and bleeds)

Halloween Special V (not just tombstones but still fun)
*Amusing Tombstones (loud scream)
*Moe falls hung from tree, opens eyes
*Reverend Lovejoy burns witches Patty and Selma, both light cigarettes
*Skinner about to be decapitated, Bart stomps down the heads already in the basket (mrs. Krabapple and Chief Wiggum), then Skinner gives a thumbs up and gets the chop