Æsir squeaked one out in MotF 59; I don't recall whether he was the first...
I was not; I was curious about that as well when MotF 59 voting was ongoing, so I went and tallied up every MotF round to that point. Majorities in bold;
(Note MotF 8, in which Bruce Munro managed to get nearly a two-thirds majority, which presumably would've granted him the right to unilaterally change the MotF Constitution 
)
MotF 1 - Sapiento - 24.00% - 2.00%
MotF 2 - Sapiento - 26.09% - 4.35%
MotF 3 - Legolas - 32.69% - 11.54%
MotF 4 - ??? - ??? - ???
MotF 5 - Nugax - 44.26% - 26.14%
MotF 6 - Scarecrow - 33.33% - 10.41%
MotF 7 - B_Munro - 44.74% - 7.90%
MotF 8 - B_Munro - 65.22% - 39.13%
MotF 9 - Krall - 40.00% - 20.00%
MotF 10 - Rubberduck3y6 - 50.98% - 27.45%
MotF 11 - B_Munro - 50.00% - 5.00%
MotF 12 - Shauckler - 30.95% - 9.52%
MotF 13 - Sir Scott - 26.25% - 7.50%
MotF 14 - Zuvarq - 45.16% - 17.74%
MotF 15 - B_Munro - 19.57% - 2.18%
MotF 16 - JMan - 31.03% - 6.89%
MotF 17 - JMan - 35.59% - 10.17%
MotF 18 - tormsen - 33.80% - 15.49%
MotF 19 - tormsen - 24.62% - 1.54%
MotF 20 - Whanztastic - 23.64% - 3.64%
MotF 21 - Ares96 / LSCatilina (Tie) - 28.77% - 19.18%
MotF 22 - Akkismat - 50.00% - 13.24%
MotF 23 - Zauberfloete - 47.89% - 35.21%
MotF 24 - Trovador - 30.26% - 11.84%
MotF 25 - rvbomally - 32.22% - 5.55%
MotF 26 - B_Munro - 54.35% - 43.48%
MotF 27 - Krall - 61.33% - 40.00%
MotF 28 - Scarecrow - 60.27% - 39.72%
MotF 29 - tormsen - 39.29% - 7.15%
MotF 30 - B_Munro - 31.71% - 9.76%
MotF 31 - Nymain1 - 48.60% - 36.45%
MotF 32 - Japhy - 35.00% - 10.00%
MotF 33 - Big Tex - 45.90% - 24.59%
MotF 34 - B_Munro - 51.06% - 10.63%
MotF 35 - Krall - 44.29% - 31.43%
MotF 36 - TheLoneAmigo - 20.22% - 4.49%
MotF 37 - Petros >Peter Fergus< - 45.45% - 30.30%
MotF 38 - B_Munro - 37.68% - 8.69%
MotF 39 - Scarecrow - 43.37% - 25.30%
MotF 40 - Ofaloaf - 45.59% - 25.00%
MotF 41 - Martin23230 - 50.00% - 29.49%
MotF 42 - Martin23230 - 50.00% - 21.28%
MotF 43 - Martin23230 - 38.20% - 7.86%
MotF 44 - B_Munro - 48.65% - 18.92%
MotF 45 - Martin23230 - 45.88% - 24.70%
MotF 46 - Horatius Cocles - 54.72% - 38.68%
MotF 47 - Martin23230 - 31.52% - 8.69%
MotF 48 - Kaiphranos - 22.06% - 2.94%
MotF 49 - tnowacki - 42.50% - 12.50%
MotF 50 - Blomma - 31.17% - 7.79%
MotF 51 - Blomma - 27.03% - 1.80%
MotF 52 - Blomma - 42.86% - 23.81%
MotF 53 - Future8 - 41.10% - 5.48%
MotF 54 - Martin23230 - 40.00% - 28.24%
MotF 55 - Pischinovski - 43.24% - 17.56%
MotF 56 - Kaiphranos / Iserlohn (Tie) - 33.96% - 23.58%
MotF 57 - Kaiphranos - 45.98% - 18.39%
MotF 58 - Kaiphranos - 47.78% - 7.78%
Since then, five more MotF rounds have concluded;
MotF 59 - Æsir - 50.70% - 32.39%
MotF 60 - Kaiphranos - 26.73% - 6.93%
MotF 61 - Krall - 38.67% - 18.67%
MotF 62 - Martin23230 - 43.00% - 24.00%
MotF 63 - Ares96 - 55.67% - 40.21%
At the time of the first list, the top five highest percentages were, in order, B_Munro in MotF 8, Krall in MotF 27, Scarecrow in MotF 28, Horatius Cocles in MotF 46, and B_Munro in MotF 26. The highest margins however, were, in order, B_Munro in MotF 26, Krall in MotF 27, Scarecrow in MotF 28, B_Munro in MotF 8, and Horatius Cocles in MotF 46; all the same rounds as highest raw percentage but in a rather different order.
Following this round, those two lists are slightly different, with Ares' entry reaching fourth by total percentage and second by margin of victory.
And, speaking of me... I didn't expect to get anywhere near winning, but three votes is slightly embarrassing.