Any fundamental papers in TCS which were found to be incorrect/wrong later?
One example is the claimed proof of the Gilbert-Pollak conjecture on the Steiner ratio, which appears in FOCS'90, and Algorithmica. The conjecture is now considered open.

Another examples include a sequence of algorithms on graph embedding.

There are more examples, but without similarly published refutations as above, it is difficulty to list due to the subtle nature.