Here is a 30-year-old version of the "Will & Grace" star all dolled up as she attended an event at the Museum of Television & Radio in Beverly Hills, California back in 1998 (left).

And, 21 years later ... the Emmy award-winning actress -- who celebrated her 51st birthday this past week -- was last spotted radiating beauty while attending a film festival in Hollywood, California earlier this month (right).

Her looks are so good, it's no wonder why they had to bring the show back!

The question is ...