Robin van Persie is now one of the footballers that can be proud of this great achievment.
We could see Lewandowski scored 4 goals against Real Madrid in semi finales last year.
Season before, we could see 2 hattricks in Round of 16. Messi scored 5 against Leverkusen, while Mario Gomez scored 4 against Basel. In both those matches teams won more then comfortably (7:0, 7:1).
Arsenal won against Porto during season 2009-2010 and Lord Bendtner scored 3 goals in that match. Same year was good one for Messi as well, who scored 4 goals in quarters against Arsenal. In the semis Ivica Olic scored hattrick for Bayern Munchen against Lyon.
Lyon also have a player who scored hatrick. In the season 2004/2005 Wiltor scored hattrick against Werder and Adriano scored 3 goals against Porto.
Probably the most famous hattrick was on that Ronaldo scored at Old Trafford. That was night to remember (season 2002/2003)
In the period before 2000, we could see hattricks from Gerrard Lopez (Valencia vs Lazio), as well as Inzaghi (AC Milan vs Dinamo Kiev) and Del Piero (Juventus - Monaco).