This is a (hopefully) complete list of the heavy artillery used by the Wehrmacht, compiled by Antonio Pena with additional info from the other members of the forum.

German Weapons
15.0 cm sFH 13 (old WW 1 equipment, only used by second line units)
15.0 cm sFH 18 (standard equipment)
15.0 cm sFH 18M (modification of sFH-18 with muzzle brake and renewable barrel liner)
15.0 cm sFH 18/40 (sFH 40 barrels on sFH 18 carriages)
15.0 cm sFH 18/43 (a sFH 18 development to accpt bag charge with sliding-block breech)
15.0 cm sFH 36 (development of sFH 18 with shorter barrel and a carriage made of alloy)
15.0 cm sFH 40 (new design, not accepted for service)
15.0 cm sFH 42 (late name of sFH 18/40)
15.0 cm sFH 43 (Krupp project, sFH 44 barrel with K 44 carriage)
15.0 cm sFH 43 (Skoda project)
15.0 cm sFH 44 (Krupp project)
15.0 cm K 16 (old WW 1 equipment, not in front line use)
15.0 cm K 18 (standard equipment)
15.0 cm K 39 (ordered by Turkey but production diverted to the Wehrmacht)
15.0 cm SK C/28 in Mörserlafette (Barrel of 15 cm Naval gun on the carriage of the 17.0 cm K 1, sometimes listed as 15.2 cm M/28)
15.0 cm Hochdruckpumpe Kanone (multichamber Kanone, experimental)
17.0 cm K 18 in Mörserlafette (one of the best guns of the WW 2)
21.0 cm lange Mórser (old WW 1 equipment, not in front line use)
21.0 cm Mörser 18 (Uses the same carriage of the 17.0 cm K 1
21.0 cm K 38
21.0 cm K 39 (Skoda built 21 cm K-52, ordered by Turkey but produced for Germany)
21.0 cm K 39/40 (revised K 39)
21.0 cm K 39/41 (another revision of the K 39)
21.0 cm K L/50 (Krupp design, not accepted for service)
24.0 cm H 39 (Skoda design for Turkey, but production diverted to the Wehrmacht)
24.0 cm H-39/40 (Development of H 39, changes for simplification of production only)
24.0 cm K L/46 (Krupp design, only a very few made, scaled.up 15.0 cm K 39)
24.0 cm K 3 (Rheinmetall design but Krupp produced)
24.0 cm K 4 (Developed by Krupp by OKH request to replace the K 3, but not completed)
28.0 cm H L/12 (Pre WW 1 design, reportedly used at Sevastopol siege in 1942)
35.5 H M-1 (Only 5 built, design with dual recoil system and 360º traverse)
42.0 H Gamma (old WW 1 equipment, used at Sevastopol siege)

Captured Weapons
14.5 cm K 405 (f) (ex-french Canon de 145 L M-16 Saint Chamond)
15.0 cm sFH 14 (ö) and (t) (ex-czech and ex-austrian M-14 Skoda)
15.0 cm sFH 15 (t) and (ö) (ex-czech and ex-austrian M-15 Skoda)
15.0 cm K 15/16 (t) (ex-czech M-15/16 Skoda)
15.0 cm sFH 25 (t) (ex-czech M-25 Skoda)
15.0 cm sFH 37 (t) (ex-czech M-37 Skoda)
15.0 cm sFH 400 (i) (ex-italian Obice da 149/12 M-14 Skoda)
15.0 cm sFH 401 (i) (ex italian Obice da 149/13 Skoda)
15.0 cm sFH 402 (j) (ex-jugoslavian M-36 S, Skoda K-1)
15.0 cm K 403 (j) (ex-jugoslavian M-28 Skoda)
15.0 cm sFH 404 (i) (ex italian Obice da 149/14 M-37)
15.0 cm sFH 406 (h) (ex-dutch sFH-13, German War reparations WW 1)
15.0 cm K 408 (i) (ex-italian Canone da 149/40 M-35)
15.0 cm sFH 409 (b) (ex-belgian sFH-13, German War reparations WW 1)
15.0 cm K 410 (i) (ex-italian Canone da 152/37, Skoda )
15.0 cm K 429 (b) (ex-belgian K-16, German War reparations WW 1)
15.0 cm K 461 (d) (ex-danish M-29 L/22 S, french Obusier M-29)
15.2 cm sFH 407 (h) (ex-dutch Howitzer 6", british BL 6 inch MK I)
15.2 cm sFH 410 (b) (ex-belgian Obusier de 6", british BL 6 inch MK I)
15.2 cm sFH 412 (e) and (i) (ex-british BL 6" Mk I and ex-italian Obice da 152/13)
15.2 cm K 433/1 (r) (ex-russian M-37 or ML-20)
15.2 cm K 433/2 (r) (ex-russian M-10/34)
15.2 cm K 435 (r) (ex-russian M-10/30)
15.2 cm K 438 (r) (ex-russian M-10/30)
15.2 cm K 440 (r) (ex-russian M-35 or BR-2)
15.2 cm sFH 443 (r) (ex-russian M-38 or M-10)
15.2 cm sFH 445 (r) (ex-russian M-09/30)
15.2 cm sFH 446 (r) (ex-russian M-10/30)
15.2 cm sFH 449 (r) (ex-russian M-17 Schneider, rebored to 15.2 cm)
15.5 cm sFH 17 (p) (ex-polish M-17, french Canon de 155 C M-17)
15.5 cm sFH 413 (b) (ex-belgian Obusier de 155, french Canon de 155 C M-17)
15.5 cm sFH 414 (f) and (i) (ex-french Canon de 155 C M-17 and ex-italian Canone da 155/14)
15.5 cm sFH 415 (f) (ex-french Canon de 155 C M-15 Saint Chamond)
15.5 cm K 416 (f) and (b) (ex-french Canon de 155 L M-17 Schneider)
15.5 cm K 417 (f) (ex-french Canon de 155 GPF-CA)
15.5 cm K 418 (f) (ex-french Canon de 155 GPF)
15.5 cm K 419 (f) (ex-french Canon de 155 GPF-Touzzard)
15.5 cm K 420 (f) and (i) (ex-french and ex-italian Canon de 155 L M-16 Saint Chamond)
15.5 cm K 422 (f) (ex-french Canon de 155 L M-77/14 Schneider)
15.5 cm K 424 (f) (ex-french Canon de 155 L M-32 Schneider)
15.5 cm K 425 (f) (ex-french Canon de 155 L M-18 Schneider)
15.5 cm K 431 (b) (ex-belgian, french Canon de 155 L M-17 Schneider)
15.5 cm K 432 (b) (ex-belgian canon de 155 L M-24)
15.5 cm K 469 (d) (ex-danish model M-29 L/22 S, rebored to 15.5 cm)
20.3 cm H 503 (r) (ex-russian M-31 or B-4)
21.0 cm Mrs 18 (t) (ex-czech M-1
21.0 cm Mrs 18/19 (t) (ex czech Mrs-18/19, mobile version of the Mrs-1
21.0 cm H 520 (i) (ex-italian Obice da 210/22, M-35)
21.0 cm K 521 (r) (ex-russian BR-17, Skoda built M-39)
22.0 cm Mörser 530 (b) (Mortier de 220 TR M 16 Schneider)
22.0 cm Mörser 531 (f) (Mortier de 220 M 16 Schneider)
22.0 cm K-532 (f) (Canon de 220 L M 17 Schneider)
22.0 cm Mörser 538 (j) and (p) (220 M 28 Skoda)
23.4 cm H 545 (b) (BL 9.2 in Howitzer MkII)
23.4 cm H 546 (e) (BL 9.2 in Howitzer MkII)
24.0 cm K 556 (f) (Canon de 240 L M 84/17 St Chamond)
24.0 cm K 559 (r)
24.0 cm K 564 (r)
24 cm Kanone (t) (First produced in 1916, continues in Czech service after WW 1)
28.0 cm H 601 (f) (Mortier de 280 M 14/16 Schneider)
28.0 cm H 602 (f)
28.0 cm H 607 (r)
30.5 cm H 622 (r)
30.5 cm H 623 (r)
30.5 cm H 638 (t) and (j) (Produced in 1916, kept in service by czech and yugoslavian armies)
30.5 cm H 639 (j) (305 mm M 11/30 Skoda)
42.0 Haubitze (t) (42 cm Hofnice M 17 Skoda, used in Sevastopol siege in 1942)
K: Kanone (Gun)
SK: Schiffs Kanone (Naval Gun)
H: Haubitze (Howitzer)
sFH: schwere Feld Haubitze (Heavy Field Howitzer)

The name Mörser was used by the Germans to class the howitzers of high calibre.

Notes
- The 17.0 cm K 18 and the 21.0 cm Möresr 18 use the same carriage.
- The 21.0 cm K 521 (r) was conceived by Skoda and exchanged by Germany after the ocupation of Czechoslovakia against raw materials
- The 20.3 cm H 503 (r) has many versions and many of them used by the Germans
- With the exception of the 15.5 GPF nearly all the french guns are used only in France and for coastal or fortress defence
The Weapons made in Czechoslovakia after the German take over are classified as German.