In Germany, it’s been forbidden to sell classical lightbulbs with more than 75 watts; instead, you’re supposed to buy more energy-efficient fluorescent devices.
However, apparently some people are selling Heatballs®… devices which fit into the same screw fittings as lightbulbs but which are (ostensibly) intended as heating devices.
And they’re very efficient at that! They convert about 95% of the electrical energy into heat, which would put them into the energy efficiency class “A”. (Some amount of light is produced as a by-product….)