Are there scientists in D&D? Should there be.....???

Sure, if you want.

Ravenloft had Doctor Mordenheim, a Frankenstein knock off and Markov, a Doctor Moreau knock off, both scientists.

D&D is basically fantasy renaissance in a number of ways and there are plenty of steampunk style D&D settings where scientists can fit right in.

Fantasy pseudo-scientists can be made with things like the technologist class from The fantastic Science: A Technologist Sourcebook for 3.5.

Dias Ex Machina Games has a bunch of scientist/technologist type classes for their Amethyst setting in a variety of game systems (3.5, 4e, 13th age).

Deadlands d20 the deadlands setting adaptation using 3.0 rules has a mad scientist class. It has its own sourcebook Way of New Science.

3.5 has the expert, if you want a real world scientist type.

Pathfinder has an alchemist class that can fill the trope. Also the technomancer prestige class for mixing high tech with magic and a couple technology themed class archetypes from the Technology Guide.

If you want a Mage the Sorcerer's Crusade type game with magic, fencing, and adventuring scientists as the theme and setting it is easy to do.

Hmm, I'm pretty sure Adventure! d20 has a scientist base class as well. Some d20 supers games likely has adventuring scientist ones as well.

ncG1vNJzZmivp6x7prrWqKmlnF6kv6h706GpnpmUqHyivsRmq6Gdopp6tK%2FInqWtoaOpwG61zWabZpxdqLWwwcudZK2glaeybq7EZ2tvaWFngHA%3D