Ned Eddard Stark is the Warden of the North. Are there any other warden besides Ned Stark? or It is a special post given to Ned Stark by Robert Baratheon (like Warden of the East, Warden of the West)
Yes there are the wardens of each compass direction, at the start of Game of Thrones those were:
- East: Vacant previously held by Jon Arryn of the Eyrie before his death.
- North: Eddard Stark of Winterfell.
- South: Mace Tyrell of Highgarden.
- West: Tywin Lannister of Casterly Rock.
All these original titles are hereditary as it is a tradition of the house.
Of course over time these positions have changed hands, due to deaths:
- Was inherited by Robb Stark after the death of his father.
- Position was abandoned when Robb rebelled during the War of the Five Kings.
- Position was re-taken by Roose Bolton after the Red Wedding.
- After murdering his father Ramsey Bolton took the position.
- Position was abandoned when Jon beat Ramsey and claimed himself King in the North.
- Jon bends the knee and takes position as Warden of the North to Daenarys though it is not official yet so the position is vacant.
- Robin Arryn inherits the title after the death of his father Jon Arryn
- The title is officially passed onto Robin by Tywin Lannister to regain their favor.
- As the Arryns appear to have aligned with the Starks it is not clear if Robin still holds the position in the Iron Throne's eyes.
- The position appears to be empty after the death of Mace Tyrell.
- The position is empty after the death of Tywin Lannister.
- Cersei and Tyrion are currently disputing the position.
According to the wiki there are also some minor wardens:
- Warden of the Prince's Pass: Lord Franklyn Fowler.
- Warden of Stone Way: Lord Anders Yronwood.
- Warden of the White Knife: Wyman Manderly of White Harbor.
Warden is a title bestowed upon the head of a Great House by the ruler of the Seven Kingdoms. The Wardens command the armies of one of the constituent regions of the Seven Kingdoms in the name of Iron Throne for the defense of the entire realm. Thus any one Warden is expected to lawfully command a quarter of all armies in the realm during a time of crisis. - wiki
Same wiki link also list all the wardens till now based on four regions west, east, north and south.
Prominent one are:
Tywin Lannister as Warden of the West, right now it seems there is no Warden in west after his death. Books do mention about Daven Lannister being appointee as warden but in show I don't remember him ever being mentioned yet. Jaime and Tyrion can be contenders but right now Castly Rock region ruler is uncertain. Jamie and Tyrion can get it based on which queen end up being on throne and whom she select. (We don't even know Jaime's clear stance).
Jon Snow as Warden of the North, he refereed "himself like that" in his letter to Sansa.
Image source - Official GoT twitter account
It can be debated if we can consider post given by Dany or not as she don't sit on Iron Throne yet but Jon write that letter after Cersei agreed with giving there help in upcoming great war (which she denied later to Jaime).
Warden of the East: Lawfully held by Robin Arryn but it's questionable now after their declaration for House Stark and Stark doesn't seems to be in position of making anyone Warden as there king Jon Snow declared Dany there queen, maybe Dany can make Robin Arryn Warden.
Warden of the South: post is also vacant for now. And nobody from Tyrell family alive now to claim it, maybe Cersie can appoint a new one.
Yes. There is one more other than North one you mentioned.
Warden is a title bestowed upon the head of a Great House by the ruler of the Seven Kingdoms. The Wardens command the armies of one of the constituent regions of the Seven Kingdoms in the name of Iron Throne for the defense of the entire realm. Thus any one Warden is expected to lawfully command a quarter of all armies in the realm during a time of crisis.
Tyrion Lannister is the Warden of the West. However, position of Warden of the East and South is currently vacant.
It is also possible that Queen Daenerys Targaryen might recognize her lord hand, Tyrion Lannister, as Warden of the West and that she might appoint him to that position should she take the Iron Throne.