PNS/M Khalid (S-137) is a diesel-electric fast-attack submarine equipped with an air–independent propulsion system and the lead ship of her class active since her commissioning in the Navy in 1999.

[1][2] Khalid, according to the Pakistan Navy, is the forerunner of her class and capable for her long-range missions in the Indian Ocean.

[5] Furthermore, the automatic control system and automation further reduces the need of crew, restricted her military staff to 36 personnel.

[11] About her commissioning, the Indian naval chief, Admiral Sushil Kumar, reportedly quoted that the "Khalid had given an edge over India.

"[12] The commissioning of the submarine was a watershed event in the country with the political elite giving credit to former Prime Minister Benazir Bhutto.