The present invention relates to an organic filler, wherein a covalent bonding of at least one organic modifier to the organic filler has been effected (i) at least via a part of the oxygen atoms of at least one functional group of the filler which is selected from phenolic OH groups, phenolate groups, aliphatic OH groups, carboxylic acid groups, carboxylate groups and mixtures thereof and/or (ii) at least via a part of the carbon atoms of the filler that are in ortho position with regard to phenolic OH groups and/or phenolate groups, a rubber composition comprising at least one rubber and at least the filler mentioned hereinabove, a vulcanizable rubber composition that additionally comprises a vulcanization system, a vulcanized rubber composition obtainable therefrom, as well as a use of the filler mentioned hereinabove for the production of (vulcanizable) rubber compositions for employment in the production of tires, preferably pneumatic tires and solid tires, preferably for their tread, sidewall and/or inner liner, respectively, and/or for employment in the production of technical rubber articles, preferably profiles, seals, dampers and/or hoses.