If we want to use a known name, maybe Halbarad would be a good choice. He certainly had a rank among the Rangers, as he commanded the group that travelled south to help Aragorn.Tolwen wrote:Arathorn got killed in TA 2933 and Aragorn was revealed his ancestry in TA 2951 (by Elrond) and probably officially declared Chieftain of the Rangers. This is IMO implied by that passage, though it is not explicitly stated in that words.Falenthal wrote:Who was the Chief of the Rangers in that time period? Arathorn, the father of Aragorn, maybe?
However, durin the 18 years in-between, probably some senior Ranger (likely descended from a previous Chieftain in a cadet branch) was likely some kind of Steward until the young heir was ready to take office. And even after that, the Rangers needed a sufficiently capable corps of senior officers to organize and keep up the watch over Eriador. From TA 2957-80 Aragorn is out adventuring on his great errantries, probably being absent from Eriador for many years at a time. Likewise, the Rangers then needed a robust system of senior "officers" - and some kind of Steward - that keep the business in Eriador up and running.
Cheers
Tolwen
http://tolkiengateway.net/wiki/Halbarad