"Testamentary partitioner" might be ok too. Also translated often as "estate distributor". Definition is "persona designada para dividir una herencia y adjudicar los bienes del causante" (person appointed to divide an estate and distribute the deceased's assets). Not necessarily the same as the executor of a will ("albacea").

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Note added at 57 mins (2016-10-25 09:48:19 GMT)
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For info, here's a description of the duties of an "albacea" (executor of a will) and "contidor-partidor" (estate partitioner/distributor).

https://tuguialegal.com/2014/08/26/albacea/


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Note added at 9 hrs (2016-10-25 18:37:44 GMT)
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To respond to Phil's assertion that both "contador-partidor" and "albacea" should be translated as "executor": The distinction made in Spanish law between "albacea" and "contador-partidor" is quite clear and I believe our translations must reflect the reality of Spanish law as accurately as possible. It is clear that "albacea" is an appropriate "functional equivalent" for "executor", given the definition of "albacea" ("persona nombrada por el testador para que encargue de dar cumplimiento a su última voluntad"). And since there is nothing quite like a "contador-partidor" in Anglo-American inheritance law (or law of succession), we must seek a translation that accurately reflects the meaning of the term in Spanish law. In view of the definition of "contador-partidor" ("persona designada para dividir una herencia y adjudicar los bienes del causante"), I believe "estate partitioner/distributor" is an appropriate rendering. Moreover, a Spanish lawyer reading a text where "contador-partidor" is translated as "executor" might assume that the translator doesn't know enough Spanish law to distinguish the two. (My two cents...)