NOTE1: As stated at Runewiki:
NOTE2: As stated at Sal's Realm of Runescape:A player's gravestone is only present in one world. This means that if the game crashes or your internet is down while you try to return to your gravestone, you must return to the world you died in to retrieve your items. If you die in one world and go into another, upon entry you will be asked if you want to go back to the world you died in.
Araxxi -- At the cave entrance, right click and choose "“Enter GraveyardÃ¢â‚¬ÂAn "instance" is a special area in RuneScape such as the area used during a boss battle. If you die in one of these areas, your gravestone will apear in the closest location outside of the instance area, rather than the exact location you died.
Automatons -- At the entrance of the the cave (north of Ardy) that leads to Guthix's Shrine
Barrows: Rise of the Six -- At the well entrance, right click and choose "“Enter GraveyardÃ¢â‚¬Â
Chaos Elemental Ã¢â‚¬â€œ None. It's the wilderness.
Corporeal Beast Ã¢â‚¬â€œ None! You have 3.5 minutes to get back before your items become visible to others. After that, they'll disappear after 1 minute more.
Dagannoth Kings -- where you died
Giant Mole -- gravestone will appear outside her lair in Falador Park.
Glacors -- where you died
GWD bosses (Commander Zilyana, General Graador, Kree'ara, K'ril Tsutsaroth) Ã¢â‚¬â€œ if you enter the God chamber normally, and you die, your gravestone will appear in the boss chamber. If you enter the God chamber after selecting an instance, your gravestone will appear in the antechamber (the room before the boss chamber)
Har-Aken (Fight Kiln) -- no gravestone. It's safe. You re-appear at the start point.
Kal'gerion demons -- inside the Daemonheim resource dungeon
Kalphite King -- in the tunnel before you enter KK's room
Kalphite Queen -- where you died
King Black Dragon (KBD) -- where you died
Legiones Ã¢â‚¬â€œ outside of the Monastery of Ascension
Muspah Ã¢â‚¬â€œ at the entrance to the World Gate
Nex -- if you enter Nex's chamber normally, and you die, your gravestone will appear in Nex's chamber. If you enter Nex's chamber after selecting an instance, your gravestone will appear in the antechamber (the room where the bank is located)
Nihils Ã¢â‚¬â€œ at the entrance to the World Gate
Queen Black Dragon (QBD) Ã¢â‚¬â€œ on the world surface near the entrance to the cave OR down in the cave near the QBD portal
Rune Dragons Ã¢â‚¬â€œ at the entrance to the World Gate
Tormented Demons -- where you died
TzTok-Jad (Fight Cave) Ã¢â‚¬â€œ outside of the entrance to the Fight Cave
Vorago Ã¢â‚¬â€œ At the cave entrance, right click and choose "“Enter GraveyardÃ¢â‚¬Â