#4 Theo Walcott
Theo Walcott joined Arsenal at the tender age of 16. He is the youngest ever player to play for England; - he made his debut aged 17 years and 75 days. This was before he had even played a competitive game for Arsenal, so this was something which at the time was seen as very controversial.
He looked set to become one of the best players in the world but due to some serious injury problems he never reached the heights that many thought he would. After scoring 108 goals in just under 400 appearances he decided to leave the club in the the 2018 Januay transfer window to join Everton.
He has made a real impact for the club and is getting regular playing time. Arsenal fans should be grateful for all the memories that he has provided. He may not have reached the heights that we all hoped, but he can be unstoppable when fully fit.