Apart from actix, we have a crate named rayon which is a work stealing based data parallelism library that makes it dead simple to write concurrent code.
Another notable crate to mention is the crossbeam crate which allows one to write multi-threaded code that can access data from its parent stack frame and are guaranteed to terminate before the parent stack frame goes away.
parking_lot is another crate that provides a faster alternative to concurrency primitives present in the standard library. If you have a use case where the standard library Mutex or RwLock is not performant enough, then you can use this crate to gain significant speedups.
