Smalltalk is, since numbers, booleans, etc. are objects, classes are objects, methods (and functions in general, known as "blocks" in Smalltalk parlance) are objects.

Likewise, the only control flow mechanism is the method call. Branching (if/then/else) is a method of the boolean objects. Loops are done via the "times" method of numbers. It's turtles all the way down.