Visitors from Maldives, Nepal, Samoa and Trinidad and Tobago do not need a visa.
Visa on arrival/ETA/e-visa is availabke for the following passport holders:
Angola, Argentina, Australia, Austria, Azerbaijan, Bahamas, Bahrain, Barbados, Botswana, Brunei, Canada, China, Costa Rica, Finland, France, Germany, Ghana, Iceland, Indonesia, Iran, Italy, Japan, Jordan, Korea (South), Korea, Republic of, Kuwait, Lithuania, Luxembourg, Malaysia, Maldives, Malta, Monaco, Mozambique, Nepal, Netherlands, New Zealand, Norway, Oman, Paraguay, Philippine, Poland, Qatar, Russian Federation, Rwanda, Saint Kitts and Nevis, Saint Lucia, Saudi Arabia, Singapore, South Africa, Spain, Sri Lanka, Sweden, Switzerland, Tajikistan, Tanzania, Thailand, Tonga, Trinidad & Tobago, Tunisia, Turkey, UAE, United Kingdom, United States, Western Samoa and Zambia.
E-visas start at US$35.
There are more countries that can get a business e-visa, but you need an invitation.
Everyone else can head to their nearest embassy and fill out some forms.
Pakistan visa on arrival countries
Pakistan Visa information
Foreign Affairs Pakistan