Is it legal to watch a discontinued series online?

Answer 1

yes

Depends.

1.If a show is so old that the copyright has expired then you can do anything.

2. On the other hand, if you are talking about a show that expired just recently - than it is likely that 'SOMEONE' has retained the right to that show. and you can't.

3. Then on the third hand: Maybe no one cares about it and you can view it all you want and no one will complain.