Abslom Daak was a comic character who first appeared in Doctor Who Monthly Magazine in 1980. He was a thuggish human criminal with a crazed vendetta against the Daleks after they killed his only love - ah the power of love thing again! He was created for the type of comic book fans who find The Hulk too cerebral and wanted to see some Conan stories in the Doctor Who universe.
His picture was briefly flashed onscreen during the Series 8 episode Time Heist, but so fast that no one could see it without veeery careful freeze-framing. So the character is not goddamn canon, just an 'easter egg' for fucking obsessive fans. Deal with it.
Unless you want to count him as canon, because he's pretty damn hardcore and awesome, in which case he totally is canon.
Official wiki canon policy this week is that only material released (not produced) in the 1980s is canon, so for the remaining 24 hours of this week, Abslom Daak is 100% canon.