Jack (died 1890) was the name of a Chacma baboon who was an assistant to a disabled railway signalman, James Wide, in South Africa.

[1] Jack was the pet and assistant of double leg amputee signalman James Wide, who worked for the Cape Town–Port Elizabeth Railway service.

[2] To assist in performing his duties, Wide purchased Jack in 1881, and trained him to push his wheelchair and to operate the railways signals under supervision.

An official investigation was initiated after someone reported that a baboon was observed changing railway signals at Uitenhage near Port Elizabeth.

[6] Jack was referenced on the second series of XFM Radio’s The Ricky Gervais Show by producer Karl Pilkington as part of his regular feature, "Monkey News".