Not so much the Lannisters as much as it is Robert Baratheon's royal court and people who serve the Lannisters.
King Robert and Lancel Lannister
Renly Baratheon and Petyr Baelish
Maester Pycelle and Varys
Ser Barristan Selmy and Ser Ilyn Payne
Thoros of Myr and Jalabhar Xho
Gregor and Sandor Clegane
Bronn and Shae