Fantom: Typesystem is unsound, far away from correctness, only hard-coded Generics, many basic things are not expressions, like if-then-else or try-catch.
Ceylon: if-then-else or try-catch are no expressions, embraces null, unstable software, breaks backward compatibility in minor releases.
Kotlin: Embraces null, inexpressive type system limits the things the compiler can check, unstable software, breaks backward compatibility in minor releases.
I am not sure what you mean by "embraces null". It sounds like a good thing (from what I know about the languages) but you have clubbed it in a list of cons.
Clojure and Scala are really the only alternative JVM languages to gain any traction since Sun/Oracle started promoting the JVM for languages other than Java.
Most of the other languages I've noticed mentioned in the comments so far (i.e. C, C++, Go, Ruby, Python, JavaScript, Haskell) don't target the JVM, and those that do just do it on the side.
Perhaps Ceylon or Kotlin will gain some traction and become a third alternative for the JVM -- all the other contenders have been around too long and lost momentum. I'd pick Kotlin over Ceylon since it can use the popular IntelliJ as a delivery platform.
Ceylon: if-then-else or try-catch are no expressions, embraces null, unstable software, breaks backward compatibility in minor releases.
Kotlin: Embraces null, inexpressive type system limits the things the compiler can check, unstable software, breaks backward compatibility in minor releases.