Crompton portrayed Eddison Tollett on the HBO high-fantasy series Game of Thrones from 2012 to 2019.

Other credits include All or Nothing (2002), Clocking Off (2001-2003), The Mayor of Casterbridge (2003), Housewife, 49, Pramface (2012-2014), The Great Fire (2014), The Suspicions of Mr Whicher, Blood (2012), Zapped (2017), Motherland (2017), Vera (2018), Marcella (2018), Peterloo (2018), and Rebecca (2020).

Crompton appeared in the 2002 film All or Nothing (2002),[3] the TV series Clocking Off (2001-2003),[3] he worked alongside Ciarán Hinds in The Mayor of Casterbridge (2003),[3] and with Victoria Wood in the Television movie Housewife, 49.

[4] He appeared in both series of the BBC TV sketch show Man Stroke Woman.

[4] He has had a recurring role as Eddison Tollett since Season 2 of the television fantasy drama series Game of Thrones.