[Legolas]

Originally Posted by littlemanpoet

One question that needs resolving: Are the "spirits in the shape of hawks and eagles [that] flew ever to and from [Manwë's] halls" (Sil p. 40) different beings than Thorondor and the Eagles that play the role of rescuer in The Hobbit and LotR?

These quotes indicate to me that they are the same.

Thorondor is sent from Manwë, and is 'mightiest of all birds that have ever been.'

And the Eagles brought news of much that passed in those days to the sad ears of Manwë. Now, even as Fingon bent his bow, there flew down from the high airs Thorondor, King of Eagles, mightiest of all birds that have ever been, whose outstretched wings spanned thirty fathoms; and staying Fingon's hand he took him up, and bore him to the face of the rock where Maedhros hung.

Thorondor's statement points out that he and his eagles are the 'Eagles of Manwë.'

But the watch of the great eagles was now redoubled, and they marked Húrin well, far below, forlorn in the fading light; and straightway Thorondor himself, since the tidings seemed great, brought word to Turgon. But Turgon said: 'Does Morgoth sleep? You were mistaken.'

'Not so,' said Thorondor. 'If the Eagles of Manwë were wont to err thus, then long ago, lord, your hiding would have been in vain.'

The term 'the great birds of heaven' indicates likewise.

But Eärendil came, shining with white flame, and about Vingilot were gathered all the great birds of heaven and Thorondor was their captain, and there was battle in the air all the day and through a dark night of doubt.

[Side note] Morgoth's limp from Fingolfin is often mentioned, but never his facial scar from Thorondor:

And Morgoth took the body of the Elven-king and broke it, and would cast it to his wolves; but Thorondor came hasting from his eyrie among the peaks of the Crissaegrim, and he stooped upon Morgoth and marred his face. The rushing of the wings of Thorondor was like the noise of the winds of Manwë, and he seized the body in his mighty talons, and soaring suddenly above the darts of the Orcs he bore the King away.

Morgoth went ever halt of one foot after that day, and the pain of his wounds could not be healed; and in his face was the scar that Thorondor made.

(all of the quotes above are from The Silmarillion)

And the eagles of The Hobbit/The Lord of the Rings are Thorondor's descendents:

There came Gwaihir the Windlord, and Landroval his brother, greatest of all the Eagles of the North, mightiest of the descendants of old Thorondor, who built his eyries in the inaccessible peaks of the Encircling Mountains when Middle-earth was young.