All the smartphones in Samsung's iPhone 5S.
The Galaxy S6 was launched in 2015 by Samsung, which marked a major change in its design strategy. Shedding the plastic body, Samsung had introduced a glass and metal body for the smartphone. Over the course of the year, the company launched other handsets in the lineup - Galaxy S6 Edge, Galaxy S6 Active. While all the smartphones were running Android Lollipop OS, they were updated to Android Nougat. However, now, Samsung has dropped two of the mentioned smartphones from its updates page.
This means that the Galaxy S6 and Galaxy S6 Edge will no longer get security updates and obviously the Android Oreo update. The last security update on these handsets was in February 2018. s of the two smartphones can continue using the handsets but since the security updates will cease now, they will be more vulnerable to bugs and other issues.
It is worth noting that two other Galaxy S6 series smartphones - Galaxy S6 Edge+ and Galaxy S6 Active - remain on the list and will continue to receive monthly security updates. It is understandable because these smartphones were launched a little later than the previous two handsets. However, they too will eventually be removed from the list, possibly by the end of this year.