King Arthur is hardly more prominent than his Knights of the Round Table in most of the romance literature on Camelot. The knights themselves are the heroes of many of the stories. Where information exists to an individual Knight of the Round Table, then you can follow that link to his own page for more information.
The big three are Sir Bedivere, Sir Gawain, and Sir Kay. Later surpassed by Sir Lancelot.
The total number of knights depends on the source you consult. The Round Table seems to have started with 50 seats, and grown, in literature anyway, through Malory's 150 to an unlikely 1600 in some.
Many of the knights of the round table only play a minor role in the legends.
A list of those Knights of the Round Table includes:-
King Arthur King Arthur himself presided
Dodinas le Savage
Ector Ector (foster Father)
Ector de Maris (bro of Lance.)
Griflet le Fise de Dieu
Harry le Fise Lake
Hervis de Revel
La Cote Mal Taile
Lamorak de Gales
Lucan the Butler
Ozanna le Cure Hardy
Urien of Gore
Yvain ( Owain, Owen)
There were of course many more Knights of the Round table, but many are only mentioned in passing in the occasional story
The Legend of King Arthur