More specifically
Mad Scientist Alphabet Blocks. Old school wood blocks with all 26 letters of the alphabet on five blocks (six illustrations per block).
A - Appendages, B - Bioengineering, C - Caffeine, D - Dirigible, E - Experiment, F - Freeze ray, G - Goggles, H - Henchmen
I - Invention, J - Jargon, K - Potassium, L - Laser, M - Maniacal, N - Nanotechnology, O - Organs, P - Peasants (with Pitchforks)
Q - Quantum physics, R - Robot, S - Self-experimentation, T - Tentacles, U - Underground Lair, V - Virus, W - Wrench, X - X-Ray
Y - You, the Mad Scientist of Tomorrow., Z - Zombies