Alien Concept Art - Looking for Feedback

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So I'm working on some designs for an upcoming project, and I have to design SO MANY ALIENS! Oi! I've been trying to get feedback from friends, but the ones who have gotten back to me haven't been super helpful, so I'm hoping that some advice from other artists will help out a little more.

Basically, each race is specifically bred for a certain task that they perform exclusively. I'm fairly sold on all of them except the Military (which is like the governor's secret police), the Businessmen, and Marketing. Input on the collection as a whole is appreciated too. Do they feel like they're from the same universe? Are there too many similarities, or something I should change about something to make it cooler/more relatable? Any input would be greatly appreciated!

Thanks!