Angela Merkel - in power since 2005 in the complicated German political system of a coalition government. This requires incredible political savvy and ability to navigate the political realm, all while having the support of a large portion of the German population. Also, she is a doctorate in Quantum Chemistry so she demonstrates immense intelligence across multiple types of measuring intelligence.
Vladimir Putin - I am not a fan by any means of his ways, but I have to give credit where credit is due in terms of the topic's question. The man came from a humble upbringing and worked his way up the KGB ranks and eventually became democratically elected and consolidated his power in a way where he achieved dictator status all while keeping the international community at bay. The man is a master manipulator of individuals (his specialty is manipulating foreign leaders from his KGB training) and is a master manipulator of the populace. He is far more cunning in this respect than anyone else is the world.
Lee Hsieng Loong - in power since 2004 in a democratic political system (Singapore) which is no easy feat. He was an honors undergraduate student in mathematics and computer science and has a master's from Harvard in Public Administration. Singapore ranks fourth in highest GDP behind tax haven and oil rich countries.
I want to address Trump as I know many of his supporters speak of his intelligence as though it's revolutionary. Let's be realistic, here: the man is not intelligent by conventional definition and, in my estimation, showcases (at best) moderate intelligence. His upbringing consisted of knowing what lies to blurt which translated into how to control the message and wiggle himself out of trouble to where it is now his best offense and defense. He's been probably the most uniquely accomplished self-marketer in our times in that sense, and has capitalized greatly on ABC's offering of having him host The Apprentice. Without this, he would never have held office. He is good at knowing where and when to capitalize on opportunity, how to gauge a general sentiment of a crowd, and his complete lack of self-awareness and/or dignity to pursue depths of absolute absurdity without hesitation makes him someone very uniquely adept at attracting a certain type of person to bond to him. While that can be considered somewhat part of social intelligence, he cannot translate his intelligence outside of that realm. We don't know for sure what his grades were like (since his lawyers made sure they would never be publicly released), we know he did not graduate with any formal distinction, and at least one previous professor of his went on record to say he was "the dumbest fucking student he ever had" (this was said far before his presidential aspirations so it couldn't have been tainted by the context of an election). He has made several objectively stupid comments related to science I do not care to repeat because we all know them, and his goldfish level memory and 6 year old with ADHD level attention span makes him someone with severe limitations, yet he overcompensates by manufacturing an Ego we see in caricatures of someone with Narcissistic Personality Disorder.
Flame me away, but I stand by what I say