Halbarad (Sindarin for High-tower) is a Ranger of the North; a kinsman, friend and follower of Aragorn. He is trying to coordinate efforts to hinder the advance of Angmar's army.
At the heart of North Downs, the last remnants of the House of Isildur gather in their hidden refuge of Esteldín. The tides of war crash against the stone walls of their encampment, but they are not yet strong enough to actively resist it and many of their number, including their chieftain Aragorn, still range far afield.
Halbarad, kinsman of Aragorn, struggles to unite the scattered peoples of the North Downs against the hordes of Orcs which have come down from Angmar through Ram Dúath. Like many of the Dúnedain of the North, Halbarad has many qualities of both a warrior and a lore-master. He uses his knowledge to coordinate efforts to hinder the advance of Angmar’s army until a stronger front can be established, all the while alert to the knowledge that he may be called to battle and fates unknown in lands far away. 
Halbarad rode to the aid of Aragorn during the War of the Ring. Leading some thirty odd Dúnedain of the Grey Company, he caught up with Aragorn at the Fords of the Isen in Rohan bearing a message from Arwen and a standard which she had made for Aragorn.
He accompanied Aragorn to a chamber high in the Hornburg, where Aragorn looked into the palantír and revealed himself to Sauron the morning prior to Aragorn's decision to traverse the Paths of the Dead under the White Mountains. Gimli, Legolas, Halbarad and the Grey Company went with Aragorn through the Paths of the Dead to summon the dead to fulfill their oath.
When they reached the entrance to the Paths, Halbarad said "This is an evil door, and my death lies beyond it. I will dare to pass it nonetheless...". He met his death in the Battle of the Pelennor Fields.
Halbarad was among the Rangers stationed at Sarn Ford in Cardolan when the Nazgûl attacked, in the evening of September 22, 3018. The survivors are still recovering when Meneldir arrives several days later. Halbarad decides later to return to Esteldín with the Rangers in force, occupying the old ruin once again.
-  Chapter 2: The Body in the Brush
-  Chapter 3: Halbarad of the Dúnedain
-  Chapter 4: Night Falls on Sarn Ford
-  Chapter 5: The South Downs
-  Chapter 9: Death On the Barrow-downs
-  Chapter 10: Spectre of the Grey Fear
-  Chapter 11: A Friend to the Dúnedain
Halbarad (Halbarad's Study)
Halbarad, he is the second-in-command of the Dúnedain behind Aragorn and leader of the Dúnedain Rangers at Esteldín. Prior to the creation of the Council of the North, he is found within his study where he formulates his plans to unite the people of the North Downs.
-  Fornost: The Darkness Within - Fellowship
-  Volume I, Book 3, Foreword: Fires in the North
-  Volume I, Book 3, Chapter 1: Ranger of the Fields
-  Volume I, Book 3, Chapter 3: Fallen Once More
-  Volume I, Book 3, Chapter 4, Part I: A Call to Dwarves
-  Volume I, Book 3, Chapter 4, Part III: The Dwarves Shall Come
-  Volume I, Book 3, Chapter 5, Part I: A Call to Elves
-  Volume I, Book 3, Chapter 5, Part III: Might of the Elves
-  Volume I, Book 3, Chapter 6, Part I: A Call to Men
-  Volume I, Book 3, Chapter 6, Part II: The Defence of Trestlebridge
-  Instance: The Defence of Trestlebridge
-  Volume I, Book 3, Chapter 6, Part III: The Free Peoples of Trestlebridge
-  Volume I, Book 3, Chapter 7: The Council Assembled
- "Those who fight Angmar at Fornost could use your strength, if you are willing to aid them."
He has said of the Hobbits:
- "A little people but of great worth are the Shire-folk. Little do they know of our long labour for the safe-keeping of their borders. Yet, I grudge it not."
Halbarad (Esteldín Library)
After the defeat of the threats posed to the Men of Trestlebridge, the Elves of Lin Giliath, and the Dwarves of Othrikar, Halbarad can be found within the Esteldín Library. It is here that the council consisting of Halbarad, Dori, Gildor Inglorion, and Nellie Boskins discuss their next steps forward.
-  Volume I, Book 15, Chapter 2: A Threat to the Dúnedain
-  Volume I, Book 15, Chapter 3: Proof's Burden
-  Volume I, Book 15, Chapter 4: Esteldín's Fate
-  Volume I, Book 15, Chapter 5: The Ring of Truth
-  Volume III, Book 1, Chapter 5: Loose Ends in the North Downs
- "These are strange times, with even stranger allies, <name>."
- "I still do not wholly trust the counsels of Narmeleth, but in this, she proved worthy."
Halbarad is temporarily found near Elrond's Stables in Rivendell. [29.3S, 6.8W]
-  Volume III, Book 2, Chapter 1: Wrought in Secret
-  Volume III, Book 2, Chapter 2: The Grey Company in Rivendell
As the Rangers move south we encounter Halbarad in several additional locations. First in Echad Eregion.
-  Volume III, Book 2, Chapter 8: As Near as May Be
-  Volume III, Book 2, Instance: As Near as May Be - Solo only
-  Volume III, Book 2, Chapter 9: The Plains of Enedwaith
Halbarad is also found at Lhanuch in Enedwaith. [66.6S, 17.4W]
-  Volume III, Book 2, Instance: An Echo of Days Past - Solo only
-  Volume III, Book 3, Chapter 3: Nona's Request
-  Volume III, Book 3, Chapter 4: Ergothorn Elf-friend - Fellowship
-  Volume III, Book 3, Chapter 8: Further Secrets
-  Volume III, Book 3, Chapter 9: Ergothorn's Last
-  Volume III, Book 3, Chapter 10: Echoes of the Dead
-  Volume III, Book 3, Chapter 11: Grief and Insight
-  Volume III, Book 4, Chapter 1: The Departure of Lhanuch
As the Rangers move into Dunland, they begin to reassemble under Halbarad.
There Halbarad is first found at Pren Gwydh at the foot of Galtrev [80.6S, 17.6W] and later at the Rohirrim Scout-camp in the Gravenwood [80.9S, 10.6W]
-  Volume III, Book 4, Chapter 3: South-east to Galtrev
-  Volume III, Book 4, Chapter 3: South-west to Galtrev
-  Volume III, Book 4, Chapter 4: The Lower Village
-  Volume III, Book 4, Instance: The Will to Stand
-  Volume III, Book 4, Rangers Put to Work
-  Volume III, Book 4, Chapter 30: The Rescue
-  Instance: The Rescue
-  Volume III, Book 5, Chapter 1: Separate Ways (Halbarad)
-  Volume III, Book 5, Chapter 1: Separate Ways (Prestadír)
-  Volume III, Book 5, Chapter 2: Grimbold
-  Volume III, Book 10, Interlude: Many Worries
-  Volume III, Book 10, Interlude: Halros's Watch
After reuniting with Aragorn at the Fords of Isen, Halbarad travels to Isengard to free Lothrandir. He can be found at the base of Orthanc. [ 45.6S, 89.0W]
-  Instance: Allies Unexpected
-  Volume III, Book 14, Chapter 7: Lothrandir
-  Instance: Lothrandir
-  Volume III, Book 14, Quest:Chapter 8: Allies of the King
As the Grey Company travels through the Paths of the Dead and into Gondor, Halbarad takes part in the summoning of the Oathbreakers at the Hill of Erech and the Battle of Pelargir. He can be found at the western gate of Pelargir near the Statue of Thorongil. [83.1S, 34.7W]
-  Instance: Those Who Are Dead
-  Book 2: Chapter 8: The Battle of Pelargir
-  Black Sails: Voices of the Past
Halbarad fights on the Pelennor before the walls of Minas Tirith. He can be found at the Ruin of Pel Dúven near midday. [18.9N, 18.3W]