This is not as easy to answer as one might suppose, we could do with some more criteria from the OP.
There have been lots of dictators the US did not support, maybe tolerated but that’s somewhat differant matter.
The main issue from the OP perspective is wether or not such dictators were generally evil in human rights abuses etc.
It’s a question of degrees really, where do you draw the line ?
Is General Musharraf supposed to be in a similar group to, say, Papa’Doc’ Duvalier.
These would be at near opposite ends of the evil spectrum I’d guess, both are responsible for classic dictatorial acts, but no-one would say the former was anything like as evil as the latter.
Here is a sample of others,
General Suharto
Muammer Qadaffi
Slobodan Milosovic
Ho Chi Minh
Juan Peron
Pol Pot
Idi Amin
Marshall Tito
Ayotollah Khomeini
Jean Bokassa
Nicolai Ceasescu
Kim Il Sung
Kamuzu Banda
Joseph Seku
Charles Taylor
General Zia
Danial Arap Moi
Haile Mengistu
Robert Mugabe
Jonas Savimbe
Hassan Al Turabai
Some of these, like Suharto, were in fact useful to the US but were discarded when they lost their usefulness, others not mentioned, such as Enva Hoxha and Najivbulla were on the Soviet side of the cold war and were merely puppets, others like Musharraf and Assad switched sides, and Jonas Savimbe carried out most of his brutal acts whilst acting as an insurgency against the recognised ‘government’ though there was not too much to choose between them.
Other notables not included woud be the Burmese Junta, every bit as horrible and brutal as the aforementioned but regarded as a collective of evil and not having a public face.
One notable was a regime that was democratic to a minority of it’s population, but as far as the rest were concerned it was a dictatorship, South Africa - in it’s apartheid years had many leaders and given the insidious nature of its opression, can be considered a pretty awful system.
Here is a list of dictators that were at one time or another, regarded as friendly to the US.
http://funkiness.com/dictators/
I notice that one all time classic that is not on that list, that was a great ally and yet the became the worst enemy is of course Joseph Stalin.