[Jarrod]

Originally Posted by Chewy

Wouldnt be surprised if Jenna was leaving, companions usually only stay 3 seasons.

Jenna is the longest serving "new-who" companion. She's stayed the longest out of all of them.

Rose Tyler:
27 episodes as main series companion [Series 1, 2 and Christmas 2005]
3 episodes as guest star companion [Series 4 episode 11-13]

Martha Jones:
13 episodes as main series companion [Series 3]
5 episodes as guest star companion [Series 4 episode 4-6, 12-13]

Donna Noble:
14 episodes as main series companion [Christmas 2006 and Series 4]
2 episodes as guest star [Christmas 2009 and New Years Day 2010]

Amy Pond:
33 episodes as main series companion [Series 5,6,7A, Christmas 2010 and 2011]

Clara Oswald:
1 episode as special guest star [Series 7 Episode 1]
36 episodes as main series companion [Series 7B, Series 8, Series 9, Christmas 2012, 2013, 2014, 50th Special]