The knights on Mordred's side who tried to arrest Lancelot in Guinevere's bedchamber were:

Sir Colgrevaunce of Gore (Slain by Lancelot in his escape)
Sir Mador de la Porte
Sir Gingalin
Sir Meliot de Logris
Sir Petipase of Winchelsea
Sir Galleron of Galway
Sir Melion of the Mountain
Sir Astamore
Sir Gromore Somir Jaure
Sir Curselaine
Sir Florence (Gawain's son)
Sir Lovel (Gawain's son)
Sir Agravain (Gawain's brother; slain by Lancelot, along with "twelve of his followers")
Sir Mordred (Gawain's half-brother; wounded by Lancelot)

   All are said by Malory to be from Scotland. Most are Gawain's kin. While rescuing Guinevere from the stake, Lancelot slays:

Sir Belliance le Orgulous
Sir Segwarides
Sir Griflet
Sir Brandiles
Sir Agloval
Sir Tor
Sir Gauter
Sir Gilmere
Sir Arnold
Sir Damas
Sir Priamus
Sir Kay the Stranger
Sir Driant
Sir Lambegus
Sir Hermind
Sir Pertelope the Green Knight
Sir Perimores the Red Knight
Sir Gaheris (Gawain's brother)
Sir Gareth (Gawain's brother)