Sir Peter Alderidge Williams KNZM QC (1 December 1934 – 9 June 2015) was a New Zealand barrister and penal reform advocate.

Williams was born in 1934 and educated at Feilding High School.

[2] A noted defence lawyer, Williams represented high-profile clients including Terry Clark, Ronald Jorgensen, Arapeta Awatere and Winston Peters, and was involved in having the conviction of Arthur Allan Thomas for the murders of Harvey and Jeannette Crewe overturned.

In 1990, he was awarded the New Zealand 1990 Commemoration Medal,[1] and in the 2015 New Year Honours Williams was appointed a Knight Companion of the New Zealand Order of Merit for services to the law.

[7][8] He died from prostate cancer at his home in the Auckland suburb of Ponsonby on 9 June 2015, survived by his wife, Lady Heeni Phillips-Williams.