Don't forget Bilbo, Faubus, Maddox, and Fulbright. Perhaps the worst of them is Hugo Black, a leading liberal Democrat senator from Alabama who pushed FDR's new deal through congress and, for his loyalty, was appointed by FDR to the US Supreme Court.
Like Byrd, Hugo Black was also a former Klan member. But whereas Byrd was a recruiter for the KKK, Black was much worse.
Black was literally a Klan attorney. He represented Klansmen who were under prosecution for hate murders. In fact that is how Black became famous in Alabama and later won his senate seat.
In 1921 a Klansman went into a Catholic church in Birmingham and murdered a priest in cold blood. He was brought up for prosecution and Klan lawyer Hugo Black signed on as his attorney. Black appealed to racial and religious hatred throughout the trial and even used his Klan connections to sway the jury. Reports of the trial note that at one point Black approached the jury, which included some Klan members, and flashed a series of Klan signals with the implication that they should acquit their fellow Klansman of the murder. They did and Black achieved his fame as the lawyer who got a fellow Klansman off the hook for a hate murder.