Miguel Esteves Cardoso was at one time a particularly prolific MetaFilter poster. He lives in Portugal, where he is a quite well-known writer (he's as well known there as, say, Tom Clancy is in the U.S. -- anyone Portuguese will have heard of him and most will be impressed that you "know" him via MetaFilter). His English is quite good: it's not the quality of the prose that makes Miguel an affectionate in-joke as well as a highly-visible poster, but rather the quantity, and the quixotic nature of some of the posts he has made in the past, particularly in MetaTalk.
Despite the exasperation he sometimes has inspired, many MetaFilter members are fond of Miguel; he has affectionately been nicknamed "Migs." He has taken most of the ribbing the community has dispensed with good humor and has reined himself in a bit. Some find it hard to dislike him for long, as he is admirably cosmopolitan, pleasant, often witty, and always has the best of intentions. Plus he knows all about the finest booze and cigars.
Miguel has only posted sporadically since November 2004.