can a beneficiary also be an executor

I practice in the state of Illinois and the answer is a resounding yes:  a beneficiary can also serve as the executor....and since everyone knows things are bigger and better in Texas, I'm going to surmise that the answer is also YES in Texas.  The prohibition you are probably thinking of is the one prohibiting a beneficiary as serving as a witness to the will.  If a beneficiary does also serve as a witness, there is a remedy-one that is not beneficial to the beneficiary, but it may vary from state to state, so check with a estate planning attorney in your locality for an answer to that one.  Hope this helps.