Donald Trump claims he has to meet with "presidents, prime ministers, dictators, kings, queens – I don’t know, somehow I don’t see it [referring to wearing a face mask] for myself." Besides the safe claim that Kim Jong-un of North Korea is a dictator, which other dictators has Trump met with during his tenure as President?
It is quite hard to determine if the leader of a country can be classified as a dictator, so I've decided to define one as the ruler of a country classified by Freedom House's 2018 report as "Not Free".
Trump has met publicly and personally with the leaders of Afghanistan, Azerbaijan, Bahrain, China, Egypt, Iraq, Khazakhstan, Libya, North Korea, Qatar, Russia, Rwanda, Saudi Arabia, Somalia, Tajikistan, Thailand, Turkey, the United Arab Emirates, Uzbekistan, Venezuela (as recognised by the US, not the current de facto President) and Vietnam.
As far as I can tell, he has not met with the leaders of Algeria, Angola, Belarus, Brunei, Burundi, Cambodia, Cameroon, CAR, Chad, DRC, Republic of the Congo, Cuba, Djibouti, Equatorial Guinea, Eritrea, Ethiopia, Gabon, Iran, Mauritania, Oman, South Sudan, Sudan, Swaziland (eSwatini), Syria, Turkmenistan, Yemen, and Zimbabwe.
Obviously at international summits it is highly likely that Trump will have met with some of these leaders behind the scenes, but it is impossible for me to speculate about private meetings.