It’s been said enough to no longer really be insightful, but Christopher Ryan as Mike in The Young Ones was excellent. But he’s even better as Dave Hedgehog in Bottom, and his appearances in One Foot In The Grave and Absolutely Fabulous are marvellous too.
It seems he has always been quietly getting on with being great, as shown by this, the first review I could find of his work, from 1971.
Or this, from a decade later …
And another …
There’s loads of examples, but you get the point.