Professional player and streamer Mikhail "Dosia" Stolyarov answered the question for Telecomasia.net who he considers the most toxic player he has ever played with.
Of all his former teammates, Dosia singled out Oleksandr "s1mple" Kostyljev, who is currently inactive in the Natus Vincere team:
Top 5 most toxic players I've ever played with? Most toxic... Well, s1mple takes the first place, it's 100%. Among the ones I've played with. That's it basically, that's the whole list.
We would like to remind you that on October 26th professional CS player Oleksandr "s1mple" Kostyljev officially announced that he took a break from playing on the competitive scene of Valve shooter.