Updated answer (No IE11 support)
img {
float: left;
width: 100px;
height: 100px;
object-fit: cover;
}
<img src="http://i.imgur.com/tI5jq2c.jpg">
<img src="http://i.imgur.com/37w80TG.jpg">
<img src="http://i.imgur.com/B1MCOtx.jpg">
Original answer
.img {
float: left;
width: 100px;
height: 100px;
background-size: cover;
}
<div class="img" style="background-image:url('http://i.imgur.com/tI5jq2c.jpg');"></div>
<div class="img" style="background-image:url('http://i.imgur.com/37w80TG.jpg');"></div>
<div class="img" style="background-image:url('http://i.imgur.com/B1MCOtx.jpg');"></div>