They not have to be marxist specifically, but all of mine are.
My favorites are: Walter Rodney, Lenin, Anuradha Ghandy and Vijay Prishad.
I have been thinking of Red Star Over the Third World again recently, and I may decide to reread it soon.
For Walter Rodney, How Europe Underdeveloped Africa is perhaps his most well known work. I have read that, and Decolonial Marxism. Both are very wonderful and comprehensive.
Anuradha Ghandy's book on feminist trends has been immensely useful for me in navigating a lot of idealistic tendencies which exist.
Her statements regarding anarchist organizing particularly is something I think of often.
It is a very short book, so it may be easier to go through as well.
And Vijay Prishad writes constantly. He is in a lot of leftist outlets being interviewed, or writing articles
The books I can think of from him are Washington's Bullets, and Red Star Over the Third World.